UNIVERSITY  OF  CALIFORNIA   PUBLICATIONS 

IN 

AGRICULTURAL    SCIENCES 

Vol.  4,  No.  1 1 ,  pp.  339-396,  2 1  figures  in  text  June  30,  1 922 


STUDIES  ON  A  DRAINED  MAESH   SOIL 
UNPRODUCTIVE  FOR  PEAS 

BY 

PAUL  S.  BURGESS 


CONTENTS 

PAGE 

Introduction    339 

Statement  of  the  Problem 341 

Methods  employed   341 

The  field  experiments - 345 

The  soil  type 345 

Variability  of  the  field  soil _ 349 

Results  of  the  plot  experiments 351 

The  greenhouse  experiments 358 

Objects  of  the  pot  experiments 360 

Treatments  employed  361 

Crop   yields   367 

Soil  extraction  studies 376 

Summary 387 

Conclusions 390 

Literature  cited 393 


INTRODUCTION 

The  unparalleled  progress  made  during  recent  years  in  chemistry 
and  physics  has  given  decided  impetus  to  the  development  of  scientific 
methods  in  soil  science  and  in  the  science  of  plant  physiology,  which 
are  rapidly  supplanting  the  older,  more  empirical  methods  of  experi- 
mentation.28* New  and  improved  procedures  are  constantly  appearing 
for  the  elucidation  of  problems  involving  a  lack  of  soil  fertility,  while 
the  fundamental  questions  of  plant  nutrition  are  being  investigated 
with  thoroughness  and  the  results  interpreted  with  discriminating 
care. 


*  Literature  cited,  pp.  393  to  396. 


340  University  of  California  Publications  in  Agricultural  Sciences       [Vol.4 

At  present,  the  more  important  factors  recognized  as  bringing 
about  a  state  of  infertility  in  soils  are : 

1.  Untoward  climatic  conditions. 

2.  Too  slight  a  concentration,  at  some  time  during  the  growth 
period,  of  one  or  more  essential  mineral  elements  dissolved  in  the  soil 
solution,  or  the  lack  in  the  solution  of  a  proper  physiological  balance 
of  ions  or  salts. 

3.  The  presence  of  substances  dissolved  in  the  soil  solution  which 
may  be  toxic  to  plant  growth ;  these  may  be  either  of  organic  or 
inorganic  nature. 

4.  Poor  physical  conditions  obtaining  in  either  the  surface  or  the 
subsoil. 

5.  A  condition  of  either  abnormal  or  subnormal  activity  on  the 
part  of  certain  of  the  soil's  micro-organic  population. 

6.  The  absence  of  sufficient  quantities  of  organic  materials  under- 
going active  decomposition. 

Until  comparatively  recently,  agricultural  chemists  and  students 
of  plant  nutrition  have  accepted  the  earlier  and  more  obvious  explana- 
tions of  most  of  these  facts  without  question,  while  the  newer  concep- 
tions went  unproved  and  unchallenged.  Now,  however,  studies  of 
cell  permeability  are  being  made,  the  questions  of  antagonism  between 
ions,  and  of  proper  physiological  balance  between  salts  in  both  soils 
and  solution  cultures  are  being  considered,  while  explanations  of 
such  observations  are  being  advanced.  The  rapidity  with  which  a 
soil  is  able  to  replenish  or  renew  solutes  absorbed  from  its  solution, 
as  well  as  the  total  concentration  at  any  given  time  during  the  growth 
period,  is  now  recognized  as  of  extreme  importance  to  continued  crop 
production.  The  use  of  the  conductivity  apparatus  and  the  cryoscopic 
method  has  given  much  valuable  comparative  data  along  these  lines, 
and  has  opened  fields  heretofore  unexplored,  while  delicate  quantita- 
tive methods  have  also  been  perfected  in  this  connection.  Great  ad- 
vances have  recently  been  made  in  the  study  of  the  nature  of  soil 
acidity  as  well  as  in  methods  for  its  accurate  determination.  And 
finally,  the  recent  investigations  in  the  realm  of  soil  colloids — the  effects 
upon  the  colloids  of  salt  applications,  as  well  as  the  direct  effects  of 
the  colloids  themselves  in  regiilating  the  concentration  of  the  soil's 
solution,  and  in  modifying  its  moisture  relations — should  receive 
merited  attention. 

Armed  with  this  knowledge,  the  soil  scientist  is  today  better  able 
than  ever  to  cope  with  the  many  obscure  and  puzzling  problems  of 


1922]  Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas  341 

low  productivity  in  soils,  which,  although  everywhere  encountered, 
are  especially  apparent  in  the  more  arid  or  semi-arid  sections  of  this 
country.  The  application  of  these  modern  methods  to  the  solution  of 
practical  field  problems  now  demands  our  attention  if  their  benefits 
are  to  be  of  direct  value  to  the  practice  of  agriculture.  To  this  end, 
the  experiments  herein  described  were  undertaken. 


Statement  of  the  Problem 

Large  areas  of  tidewater  and  overflow  lands  bordering  the  San 
Pablo  and  San  Francisco  bays  and  the  Sacramento  and  San  Joaquin 
rivers  have  in  the  past  been  drained  and  are  at  present  used  to  grow 
a  variety  of  crops.  Certain  areas  within  these  reclaimed  sections, 
varying  in  extent  from  an  acre  to  many  hundreds  of  acres,  are  unpro- 
ductive for  certain  crops.  The  study  discussed  in  this  paper  deals 
with  a  careful  investigation  of  one  partially  unproductive  area  com- 
prising about  a  thousand  acres,  located  at  Ignacio,  California,  on 
the  property  of  the  California  Packing  Corporation.  The  owners  of 
this  ranch  were  especially  desirous  of  growing  peas  for  canning  pur- 
poses on  the  land  under  experiment,  but  have  had  very  poor  crops 
during  the  past  few  years.  The  peas  ordinarily  sprout  and  come 
up  well,  but  when  five  or  six  inches  high,  turn  yellow  and  gradually 
die.  A  few  plants  of  each  crop  always  mature,  but  hardly  a  third  of  a 
normal  crop  usually  is  harvested.  "When  we  consider  that  there  are 
thousands  of  acres  of  similar  lands  in  California  which  have  been 
drained  and  brought  under  cultivation  at  great  expense,  the  importance 
of  a  careful  and  thorough  study  of  this  problem  can  hardly  be  over- 
emphasized. 

METHODS  EMPLOYED 

As  has  been  stated,  one  of  the  main  objects  of  the  present  investiga- 
tion was  to  test  the  applicability  of  certain  modern  methods  of  soil 
research  to  the  solution  of  a  practical  field  problem.  Among  those 
methods  which  have  recently  come  into  considerable  prominence  may 
be  cited  the  periodical-water-extraction  procedure,  which  has  been 
largely  developed  and  standardized  by  the  work  of  Burd,5  Hoagland,21 
and  Stewart.44  The  water  extraction  idea  for  soil  investigations  is 
not  a  new  one.    It  has  been  used  in  Europe  for  over  sixty  years,*  and 


An  extensive  bibliography  is  given  by  Stewart.4* 


342  University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 

twenty  years  ago  iu  this  country,  King25, 2G  applied  it  to  comparative 
fertility  work  in  the  field.  Also,  in  the  method  proposed  by  Burd  and 
his  associates  the  extraction  procedure  and  certain  other  details  are 
quite  similar  to  those  used  by  our  Federal  Bureau  of  Soils  many  years 
ago.  The  difference  between  the  two  lies  in  the  manner  of  application 
to  the  problem,  and  in  the  method  of  interpreting  the  results.  One  of 
the  chief  points  of  weakness  attaching  to  the  procedures  of  the  earlier 
workers,  and  never  satisfactorily  overcome  by  them,  has  now  been 
surmounted  through  the  careful  and  painstaking  work  of  Stewart,44 
Hibbard,19'  20  and  others.  I  refer  to  methods  of  chemical  analysis  of 
the  soil  extract.  In  the  earlier  work,  analytical  methods  were  usually 
far  too  crude  to  differentiate  between  the  slight  differences  often  obtain- 
ing. Inaccurate  colorimetric  methods  were  then  the  rule.  Today, 
these  have  largely  been  supplanted  by  volumetric  and  gravimetric 
procedures  which  insure  more  accurate  results.  The  general  method 
of  experimentation  mentioned  above  is  given  in  detail  by  Stewart.14 

During  the  past  few  years  several  field  tests  with  fertilizers  have 
been  made  upon  the  soil  under  study.  The  application  of  lime  has 
occasionally  increased  yields  somewhat,  and  the  addition  of  super- 
phosphate has  consistently  improved  conditions,  although  the  cost  of 
the  applications  has  not  always  been  met.  A  preliminary  examination 
made  by  the  writer  showed  the  soil  to  be  very  acid  in  reaction,  while 
the  deeper  layers  of  the  subsoil  carried  large  quantities  of  the  "white 
alkali"  salts,  notably  sulfates. 

With  the  results  and  methods  just  discussed  in  mind,  it  was  decided 
to  conduct  two  series  of  experiments:  first,  a  set  of  plot  tests  in  the 
field,  applying  superphosphate  to  certain  plots  and  liming  others  to 
neutrality,  proper  checks  being  maintained ;  and,  second,  a  pot  experi- 
ment with  various  soil  amendments,  to  be  carried  out  in  the  greenhouse 
on  the  campus  of  the  University  of  California;  the  same  soil  to  be  used 
and  peas  to  be  grown  in  both  cases.  The  two  crops  were  to  be  planted 
at  the  same  time,  and  soil  samples  were  to  be  drawn  periodically 
from  each,  extracted  and  analyzed.  Soil  reaction  under  the  growing 
crops  was  also  to  be  closely  followed,  while  alkali  determinations  were 
to  be  made  from  time  to  time  in  the  field  soil.  The  presence  or  absence 
of  soluble  organic  soil  toxins  could  also  be  noted  by  the  application  of 
an  excess  of  CaC03,  for  Truog  and  Sykora45  have  shown  such  poisonous 
constituents  to  be  rendered  innocuous  in  soils  by  the  complete  neutrali- 
zation of  soil  acidity  as  well  as  by  the  use  of  certain  other  soil  amend- 
ments. 


1922]  Burgess:  Studies  on  Marsh  Soil  Unproductive,  for  Peas  343 

Both  the  field  and  the  pot  soils  were  sampled  every  four  weeks 
during  the  growing  period  except  as  noted  below.  A  sample  was 
drawn  from  directly  beneath  the  row  of  growing  plants,  from  four 
places  in  each  plot  (see  fig.  1),  care  being  taken  to  obtain  a  repre- 
sentative sample  down  to  a  depth  of  7  inches  (surface  soil).  The 
twelve  individual  samples  from  the  checks  and  a  like  number  from  the 
phosphate  plots  were  then  mixed  very  thoroughly  and  quartered  down 
for  the  final  composite  samples.  These  were  brought  at  once  to  the 
laboratory,  passed  through  a  2  mm.  sieve,  and  placed  in  tight  Mason 


7o/9c7>£  Plots 

' 

*6 

• 

' 

° 

#5  (pzo.)  ' 

• 

° 

O 

#4. 

• 

> 

• 

#3  (n°s) 

0 

' 

■ 

*2 

• 

° 

• 

*l  (n°s)   ° 

1 

JfB 


Fig.  1. — Method  of  sampling  plot  soils. 

jars,  after  withdrawing  sufficient  soil  for  moisture  determinations. 
The  proper  amounts  of  the  moist  soils,  the  percentages  of  moisture 
being  taken  into  consideration,  were  then  weighed  out  to  make  300  g. 
of  water-free  soil,  to  which  sufficient  distilled  water  was  added  to 
bring  the  proportion  of  water  to  soil  up  to  exactly  5  to  1.  The  mix- 
tures of  soil  and  water  were  now  shaken  for  one  hour  in  an  end- 
over-end  shaking  machine,  running  at  a  speed  of  7  revolutions  per 
minute.  Settling  was  allowed  to  take  place  overnight,  after  which  the 
supernatant  liquids  were  siphoned  off  and  filtered  through  Pasteur- 
Chamberland  filters.  The  resulting  clear  solutions  were  used  for 
analysis  by  methods  which  will  be  given  later.  Hydrogen-ion  deter- 
minations were  made  upon  portions  of  the  moist  soils  as  soon  as 
received  at  the  laboratory.  The  hydrogen  electrode  described  by 
Sharp  and  Hoagland42  was  employed. 


3-1-1  University  of  California  Publications  in  Agricultural  Sciences       [Vol.4 

In  the  greenhouse  pot  experiment  a  sharp  small-bore  18-inch  cheese 
trier  was  used  in  sampling,  each  core  being  taken  from  the  entire 
depth  of  soil.  In  order  to  obtain  sufficient  soil  for  the  water  extrac- 
tions, it  was  necessary  to  take  three  cores  from  each  pot  at  each 
sampling.  The  resulting  holes  were  always  filled  with  similar  dry, 
untreated  soil.  Proper  precautions  were  employed  to  avoid  subse- 
quent sampling  in  the  same  places.  The  moist  soils  were  placed  at 
once  in  tight  Mason  jars  and  hydrogen-ion  determinations  and  extracts 
were  subsequently  made  in  exactly  the  same  way  as  described  for  the 


O00000000000000© 
000000©©©©©©©©©© 


0000Q©0000©©Q0©0 


Fig.  2. — Arrangement  of  pots  in  greenhouse  experiment. 

field  samples.  Conductivity  measurements  were  made  upon  the  ex- 
tracts at  each  sampling.  The  simple  Kohlrausch  conductivity  outfit 
was  employed.  A  detailed  description  of  the  apparatus,  together  with 
conversion  tables,  is  given  by  Oswald  and  Luther39  (pp.  461-477). 
The  specific  resistances  (in  ohms),  rather  than  their  reciprocals,  the 
specific  conductivities,  have  been  employed  in  the  work  hereafter 
reported. 

The  clear  soil  extracts  were  regularly  analyzed  for  the  following 
ions,  Ca,  Mg,  K,  P04  and  N03,  supplemented  by  occasional  deter- 
minations of  S04,  CI,  and  Al.  Carbonates  and  bicarbonates  were 
usually  absent  except  where  lime  was  used.  The  P04-,  Ca-,  and  K-ions 
were  determined  in  accordance  with  the  methods  proposed  by  Stewart41 
(pp.  328,  329),  except  that  600  cc.  aliquots  were  found  necessary  in 
the  case  of  P04-ion,  while  400  cc.  portions  were  used  for  Ca  and  K. 


1922]  Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas  345 

Nitrates  and  chlorides  were  run  by  the  phenoldisulphonic  acid  method 
and  by  titration  with  a  standard  silver  nitrate  solution,  respectively. 
These  methods  are  essentially  those  widely  used  in  sanitary  water 
analysis.1  Magnesium  was  determined  gravimetrically  as  the  pyro- 
phosphate in  the  filtrate  from  the  calcium  oxalate  precipitate,  after 
first  evaporating  to  dryness  and  burning  off  ammonium  salts.  Sul- 
fates were  determined  gravimetrically,  weighing  as  BaS04.  Six  hun- 
dred cc.  aliquots  of  the  original  soil  extracts  were  first  evaporated  to 
dryness,  burned  off,  and  taken  up  in  very  dilute  hydrochloric  acid 
before  precipitation  with  barium  chloride.  The  water-soluble  sodium, 
silica,  and  aluminum  were  occasionally  determined.  In  all  cases  ali- 
quots were  taken  large  enough  to  make  possible  the  use  of  standard 
gravimetric  procedures. 

At  the  beginning  of  the  work  many  determinations  were  made 
upon  identical  extracts  in  order  to  check  up  the  results  as  regards 
accuracy  of  duplication.  As  a  rule,  the  larger  the  amounts  of  the 
various  ions  present,  the  more  accurate  would  be  the  determinations. 
For  instance,  in  the  case  of  K,  when  that  ion  was  present  above 
40  p.  p.  m.  (as  was  usually  the  case),  duplicate  determinations  in- 
variably checked  within  less  than  3  p.  p.  m.  In  other  words,  the  per- 
centage variation  between  duplicates  was  here  under  8  per  cent. 
Better  checks  than  this  were  usually  obtained  with  Ca,  Mg,  NO,,  and 
CI,  while  with  P04,  duplicates  might  differ  by  1  p.  p.  m.  when  present 
in  quantities  of  less  than  5  p.  p.  m.  The  very  small  amounts  of  phos- 
phorus always  present  in  these  soil  extracts  made  this  element  un- 
usually difficult  to  determine  accurately.  Sulfates  always  checked 
well  in  duplicate  determinations. 

Stewart44  (pp.  332,  333)  has  discussed  very  fully  the  form,  or 
method,  of  recording  final  results,  and  until  more  is  definitely  known 
about  the  true  soil  solution,  it  seems  best  to  the  writer,  also,  to  express 
all  results  as  "parts  per  million  of  dry  soil."  This  procedure  has 
been  followed  throughout. 


THE   FIELD   EXPERIMENTS 
The  Soil  Tijpe 

The  soil  at  Ignacio  has  been  formed  by  the  deposition  of  clay  and 
very  fine  silt  brought  down  by  the  Sacramento  River.  It  is  a  light 
drab  clay  loam  underlain  at  a  depth  of  six  to  seven  inches  by  a  very 
deep,  almost  impervious,  clay  subsoil  of  lighter  color.     Neither  the 


346 


University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 


surface  nor  the  subsoil  contains  gritty  particles  of  any  kind  and  when 
wetted,  both  are  extremely  smooth,  plastic,  and  sticky.  Aeration  is 
thus  always  poor  and  deep  root  development  impossible.  The  apparent 
specific  gravity  of  the  surface  soil  when  air  dried  and  heavily  com- 
pacted is  0.970.  An  acre  to  a  depth  of  6  inches  thus  weighs  about 
1,320,000  pounds  or  660  tons.  Its  light  weight  is  due  chiefly  to  the  13 
per  cent  of  organic  matter  which  it  contains.  The  total  water  holding 
capacity  (Hilgard  method)  is  104%  of  the  moisture-free  soil.  The 
optimum  moisture  holding  capacity  is  thus  not  far  from  50%  while 
the  hygroscopic  coefficient  is  14%. 

Chemically,  the  soil  presents  a  number  of  very  interesting  features. 
An  analysis  made  by  the  Hilgard  method  (digestion  for  40  hours  at 
100°  C.  in  HC1,  sp.  gr.  1.115)  on  a  representative  composite  sample 
from  the  poor  area  under  study  appears  in  Table  I.  Only  those  ele- 
ments important  to  a  discussion  of  plant  nutrition  were  determined. 
The  table  also  gives  the  amounts,  in  parts  per  million,  of  the  various 
ions  (computed  as  the  oxides  for  comparison)  soluble  in  water,  deter- 
mined by  the  methods  previously  described. 


TABLE  I 

Chemical  Analysis  of  Ignacio  Soil 

(Eeduced  to  water-free  basis) 

Strong  Acid  Water- 

Soluble  Per  Soluble 

Cent  p.  p.  in. 

Insoluble  matter  (Si02)  58.60  55 

Potash    (K,0) 0.23  54 

Soda    (NaJD)    286 

Lime   (CaO)   0.66  125 

Magnesia   (MgO)    1.34  75 

Iron  (Fe203)  "I  none 

Alumina  (ALA,)   I         21'15  24 

Phosphoric  Acid  (P205)  '••           0.25  4 

Sulfuric  Acid  (SO,)  0.62  400 

Total  nitrogen  (N)  0.36 

Nitrates   (NO,)    150 

Chlorine  (CI)   100 

Loss  on  ignition    (volatile)    13.25  

Manganese  was  practically  absent,  as  were  also  carbonates  and  bicarbonates. 
Negative  tests  were  noted  for  ferrous  salts. 

These  results  are  inserted  merely  to  show  the  general  chemical 
composition  and  the  relative  solubilities  of  this  soil.  It  is  interesting 
to  observe  the  reversed  "lime-magnesia  ratio"  when  total  percentages 
of  these  compounds  are  compared  with  their  water-soluble  portions ; 


1922]  Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas  347 

also  that  the  phosphoric  acid,  although  not  low  in  total  percentage,  is 
but  very  slightly  soluble  in  water.  High  amounts  of  available  potassium 
as  well  as  the  presence  of  considerable  quantities  of  water-soluble 
aluminum  are  also  shown. 

As  this  soil  was  at  one  time  below  the  level  of  San  Pablo  Bay,  it 
was  thought 'desirable  at  the  inception  of  the  work  to  make  a  careful 
alkali  survey  of  the  area,  especially  of  that  portion  of  it  where  it  was 
later  planned  to  conduct  the  field  experiment.  Accordingly,  about 
40  samples  of  surface  soil  were  taken.  Several  borings  were  also  made 
to  a  depth  of  5  feet,  the  1-foot  samples  being  segregated  and  quanti- 
tatively analyzed  for  water-soluble  chlorides  and  sulfates.  Carbonates 
were  absent.  Bicarbonates  were  present  in  traces  only.  Table  II 
presents  the  data  secured.  The  figures  for  the  surface  soil  are  averages 
of  40  analyses,  all  of  which  agreed  fairly  closely.  The  subsoil  samples 
(except  top  foot)  are  averages  of  duplicate  borings.  The  number  of 
samples  averaged  appears  in  the  table. 

TABLE  II 

Alkali  Determinations 

NaCl  Na2S04 

Per  Cent.*  Per  Cent.* 

Surface,  6  to  7  inches  (40  samples)  0.018  0.066 

Sub-soil,  1st  foot  (20  samples)  .100  .180 

Sub-soil,  2d  foot   (2  samples)    .150  Heavy  testt 

Sub-soil,  3d  foot   (2  samples)  .450  Heavy  test 

Sub-soil,  4th  foot   (2  samples)    .710  Heavy  test 

Sub-soil,  5th  foot   (2  samples)    .880  Heavy  test 

The  percentages  of  alkali  present  in  the  surface  soil,  although  con- 
sidered small,  may  possibly  approach  toxic  concentrations  where  limited 
moisture  conditions  prevail.  The  large  quantities  of  soluble  salts  in  the 
subsoil  probably  exert  no  direct  effect,  for  plants  are  seldom  able  to 
root  there  below  12  inches  on  account  of  the  impervious,  compact  con- 
dition of  the  soil.  That  alkali  and  subsequent  leaching  have  in 
the  past  contributed  to  these  untoward  conditions  is  probable.  The 
work  of  Sharp,41  as  well  as  that  of  Hager,15  has  shown  that  soils,  espe- 
cially heavy  clays,  once  saturated  with  solutions  of  soluble  salts,  or 
inundated  with  sea  water  and  later  washed  free,  are  almost  invariably 
left  in  a  very  poor  and  impervious  physical  condition. 

*  Percentages  figured  to  dry  soil  basis.  The  surface  soil  contained  6%  water 
(air  dry),  while  the  subsoil  carried  an  average  of  34%  water  when  received  at 
the  laboratory. 

t  The  writer  did  not  quantitatively  determine  the  sulfates  in  these  samples. 


348  University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 

The  next  factor  to  receive  attention  was  soil  reaction.  Peas  were 
to  be  grown  and,  in  the  past,  a  neutral  or  slightly  alkaline  reaction  has 
been  advocated  for  this  crop.  The  Ignacio  soil  was  found  to  be  ex- 
tremely acid.  The  hydrogen-ion  concentration,  as  determined  on  a 
large  number  of  fresh  field  samples,  gave  an  average  exponential  value 
of  PH  =  4.-16.  A  preliminary  experiment  to  ascertain  the  approximate 
lime  requirement  was  performed  after  the  method  of  eleetrometric 
titration  with  a  standard  solution  of  Ca(OH),  as  proposed  by  Sharp 
and  Hoagland.42  Considering  an  acre-six-inches  of  this  soil  to  weigh 
660  tons  (see  above),  it  was  found  that  4  tons  of  calcium  carbonate 
were  immediately  required  to  neutralize  the  concentration  of  hydrogen- 
ion  present.*  An  experiment  was  now  set  up  using  100-gram  por- 
tions of  the  field  soil  and  thoroughly  mixing  each  with  different 
amounts  of  pure  CaC03.  Optimum  moisture  conditions  were  main- 
tained. Table  III  shows  the  lime  treatments,  together  with  the  PH 
values  as  determined  from  time  to  time. 


TABLE  III 

Lime  Reql 

UREMENT 

OF 

Field  Soil 

Tons 

CaC03 

per-Acre 

Grams 

CaC03 

per  100 

Grams  Soil 

PH 

Number 

After 
1  week 

After 
1  month 

After 
5  months 

After 
7  months 

1 

3 

0.45 

6.3 

5.7 

5.5 

5.4 

2 

4 

0.60 

7.0 

6.0 

5.9 

5.9 

3 

5 

0.75 

7.1 

5.3 

6.1 

5.5 

4 

6 

0.90 

7.2 

6.6 

6.6 

6.5 

5 

8 

1.20 

7.4 

7.1 

7.2 

7.1 

6 

10 

1.50 

7.6 

7.2 

7.2 

7.2 

Considering  PH  =  7  to  indicate  a  state  of  neutrality,  a  glance  at 
this  table  shows  that  a  field  application  of  7  or  8  tons  of  lime  carbonate 
per  acre  would  be  necessary  to  insure  a  slightly  alkaline  soil  reaction 
for  approximately  the  growing  period  of  a  crop.  The  fact  that  larger 
and  larger  amounts  of  lime  are  required  upon  standing  would  indicate 
that  hydrogen-ions  are  being  progressively  and  rapidly  formed.  This 
may  be  due  to  a  decomposition  of  organic  matter  with  subsequent 
formation  of  nitric  acid  and  the  less  soluble  organic  acids,  to  silicate 
degradation,  or  to  the  hydrolysis  of  soluble  aluminum  compounds. 


*  Recent  work*. 24  has  intimated  that  there  may  be  a  relation  between 
Ph  and  lime  requirement,  whereby  the  latter  may  be  indirectly  and  rapidly 
determined,  but  it  appears  to  the  writer,  as  well  as  to  Knight,27  that  mueh 
work  still  remains  to  be  done  before  any  general  comparisons  are  possible. 


1922] 


Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas 


349 


Variability  of  the  Field  Soil 

It  is  in  no  wise  the  intention  of  the  writer  to  enter  into  a  detailed 
discussion  of  the  factor  of  variability  as  applied  to  the  study  of  field 
soils.  The  work  herein  reported  was  planned  for  other  purposes. 
Variability  studies  have  been  recently  attempted  by  Waynick47  and 
by  Waynick  and  Sharp48  with  some  measure  of  success.  That  seem- 
ingly uniform  soils  may  vary  greatly  both  chemically  and  biologically 
within  very  small  areas  has  been  well  and  forcibly  brought  out  by  these 
investigators,  and,  as  an  excellent  opportunity  was  here  presented  for 
obtaining  further  data  along  this  line  (where  water  extracts  were 
concerned),  a  number  of  analyses  are  reported  showing,  for  the  field 
soil  under  discussion,  the  varying  tendencies  of  the  "total  soluble 
solids,"  the  Ca-,  K-,  N03-,  and  the  Cl-ions.  The  location  chosen  for 
the  field  plot  experiment  was  the  area  whence  these  samples  came 
and  was  in  all  respects  as  uniform  in  texture,  color,  and  appearance 
as  one  could  well  find.  It  was  unusually  level,  being  comparatively 
free  from  slight  local  elevations  or  depressions  so  often  present  in 
otherwise  uniform  fields.  For  miles  in  all  directions  but  slight  visible 
differences  could  be  detected.  The  locations  of  samples  are  shown  in 
the  accompanying  diagram  of  the  field  plots. 

Diagram  of  Field  Plots 
l-10th  acre  plots  l-5th  acre  plots 


X 

X 

6 

X 

X 

X 

X 

9 

X 

X 

X 

X 

5 

X 

X 

X 

X 

X 

X 

X 

X 

4 

X 

X 

X 

X 

8 

X 

X 

X 

X 

3 

X 

X 

X 

X 

X 

X 

X 

X 

2 

X 

X 

X 

X 

7 

X 

X 

X 

X 

1 

X 

X 

X 

X 

X 

X 

Table  IV  presents  the  analytical  results  secured.  Before  com- 
puting the  results  as  presented,  they  were  in  each  case  plotted  and 
shown  to  form  a  proper  frequency  curve.  This  justifies  the  use  of 
the  statistical  method  in  connection  with  these  data. 

As  will  be  seen,  not  all  of  the  48  samples  were  analyzed  in  each 
case,  but  sufficient  determinations  were  made  to  show  prevailing  con- 


350 


University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 


ditions.  As  duplicate  extractions  of  the  same  sample  seldom  varied  by 
more  than  8%  to  10%  for  any  of  the  ions  determined  (and  often  by 
much  less),  and  as  the  coefficient  of  variability  (which  is  nothing  more 
than  the  standard  deviation  expressed  as  its  percentage  of  the  mean 
or  arithmetical  average)  varies  from  12%  in  the  case  of  K-ion  to  over 
44%  in  the  case  of  N03-ion,  there  can  be  no  doubt  that  apparently 
uniform  field  soils  are  likely  to  vary  greatly  from  place  to  place  in 
water-soluble  constituents ;  and  it  is  evident  that  only  averages  of 
very  large  numbers  of  single  determinations  or  analyses  of  carefully 
composited  samples  drawn  from  a  considerable  number  of  separate, 
uniformly  distributed  stations  over  areas  under  examination  can 
give  dependable  results  or  significant  differences.     Thus  the  work  of 


TABLE  IV 

Variability  of  the  Field  Soils  as  Regards  Minerals 
(Parts  per  million  of  dry  soil) 


Calcium- 

Potassium- 

Total  Sol. 

Nitrate- 

Chloride- 

Sulfate- 

ion  (Ca) 

ion  (K) 

Solids 

ion  (N0») 

ion  (CI) 

ion  (S0«) 

62 

57 

3215 

310 

120 

986 

49 

54 

2540 

265 

111 

520 

51 

44 

2350 

288 

110 

296 

48 

61 

2125 

350 

120 

444 

340* 

44 

3175 

243 

125 

574 

55 

44 

2300 

177 

130 

499 

59 

54 

2300 

199 

120 

355 

59 

44 

1975 

133 

130 

383 

278* 

53 

2500 

221 

125 

316 

92 

56 

2000 

203 

125 

358 

440* 

48 

1950 

350 

in 

432 

55 

44 

1475 

203 

125 

327 

60 

48 

3075 

221 

310* 

381 

55 

55 

2175 

420 

110 

361 

66 

42 

1825 

310 

105 

449 

52 

39 

2675 

265 

95 

358 

62 

44 

1800 

221 

95 

419 

59 

46 

2700 

203 

100 

386 

51 

49 

1975 

203 

95 

363 

50 

40 

1525 

111 

93 

367 

70 

49 

1250 

88 

90 

399 

63 

48 

3000 

99 

85 

385 

481* 

42 

1825 

88 

75 

348 

50 

39 



111 

80 

366 

201* 

56 

Mean  =2244  ±74 

221 

100 

460 

69 

56 

S.D.  =527  ±52 

133 

90 

424 

60 

55 

C.V.  =23.5  ±2.3% 

155 

95 

659 

56 

53 

P.E.  =  ±355 

111 

100 

378 

87 

— 

97 

90 

388 

75 

Mean  =49  ±.67 

97 

85 

658 

69 

S.D.  =6±53 

177 

86 

399 

191* 

C.V.  =12.2±1.1% 

115 

90 

644 



P.E.  =  ±4.0 

177 

100 

392 

Mean  =61  ±1.5 

142 

150 

409 

S.D.  =  10.9±1.1 

97 

95 

611 

C.V.  =  18±1.7% 

115 

75 

457 

P.E.  =  ±7.4 

350 

85 

■ 

155 

100 

Mean  =42S  ±10.9 

155 

100 

S.D.  =95±7.7 

111 

75 

C.V.  =22.3  ±1.8% 



— — 

P.E.  =  ±64.4 

Mean  =  192  ±9.2 

Mean  =  102±1.9 

S.D.  =86  ±6.4 

S.D.  =17.6  ±1.3 

C.V.  =44.8  ±3.4% 

C.V.  =  17.2  ±1.3% 

P.E.  =  ±58.0 

P.E.  =  ±11.8 

♦Omitted  from  mean. 


1922]  Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas  351 

Waynick  and  Sharp  on  soil  variability*  has  been  confirmed  and  shown 
to  hold  for  certain  water  extractable  materials  as  well  as  for  nitrates, 
total  nitrogen  and  organic  carbon. 

Results  of  the  Plot  Experiments 

A  brief  history  of  the  management  of  the  area  under  study  follows : 
1913  and  1914:  Reclaimed  from  salt  marsh  by  diking  and  drain- 
age. 
1915:  Planted  to  grain  hay.    Good  yields  (3  to  3i/>  tons  per  acre). 
1916 :  Planted  to  peas.    Failure. 
1917:  About  one  ton  per  acre  of  "beet-lime"  (85%  CaC03)  added 

and  peas  again  planted.  Failure. 
1918 :  Planted  again  to  peas.  At  first  the  crop  came  along  nicely, 
but  about  the  middle  of  March,  when  the  peas  were  two- 
thirds  grown,  they  suddenly  began  to  die  out.  Small  appli- 
cation of  lime  apparently  had  little  effect.  The  crop  was 
a  failure.  After  the  peas  failed  the  land  was  immediately 
plowed  and  beans  were  planted.  A  very  poor  crop  resulted — 
about  700  pounds  per  acre. 
1919:  Sugar  beets  were  grown.    A  poor  crop  resulted  (between  3 

and  4  tons  of  small  beets  per  acre). 
1920 :  A  large  part  of  the  poor  land  was  again  planted  to  sugar 

beets. 
Much  care  was  exercised  in  locating  the  experimental  plots  and  in 
their  subsequent  oversight  and  treatment.  Neither  fertilizers  nor  soil 
amendments  had  previously  been  applied  to  this  area,  although  small 
applications  (1  ton  per  acre)  of  lime  had  been  used  on  adjacent  sec- 
tions. About  one  and  one-fifth  acres  (a  piece  125x450  feet)  was 
measured  off  during  the  month  of  July,  1919,  and  after  the  removal 
of  a  poor  crop  of  sugar  beets,  was  plowed  and  disked  prior  to  planting. 
Six  one-tenth  acre  plots,  20x218  feet,t  were  laid  out  as  were  also 
three  one-fifth  acre  plots,  40x218  feet  (see  diagram  above).  The 
smaller  plots  were  numbered  from  one  to  six,  and  superphosphate 
(18.1%  water-soluble  and  20.0%  total  P,05)  at  the  rate  of  1  ton  per 


*  For  a  full  and  detailed  account  of  the  statistical  method  as  applied  to  the 
interpretation  of  biochemical  results  the  reader  is  referred  to  the  papers  of 
Waynick  already  cited,  to  Wood,50-  5i  and  to  Davenport.10 

t  The  plots  were  made  long  and  narrow  to  facilitate  working  and  harvesting 
by  standard  machinery.  Lyonso  has  also  shown  that  long  and  narrow  plots 
give  most  dependable  results. 


352  University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 

acre  was  applied  to  the  odd  plots  while  the  even  ones  received  no 
treatment  (checks).  The  center  one-fifth  acre  plot  (Number  8)  was 
left  untreated  while  Number  7  received  finely  ground  limestone 
(99.6%  CaC03)  and  Number  9,  sugar  beet  lime  (87%  CaC03),  both 
at  the  rate  of  10  tons  per  acre.  These  applications  were  slightly  in 
excess  of  the  lime  requirements  for  the  surface  soil  (see  page  348). 
The  phosphate  and  lime  applications  were  thoroughly  disked  into  the 
surface  soil  about  two  weeks  before  planting. 

The  peas  (Horseford's  Market  Garden  Variety)  were  planted  on 
October  26,  1919,  in  rows  30  inches  apart,  one  inch  apart  in  the  rows. 
There  were  thus  8  rows  in  the  smaller  and  16  rows  in  the  larger  plots. 

Since  an  important  part  of  the  plot  experiment  was  the  observation 
of  the  varying  concentration  of  the  soil  solution  under  both  the  fer- 
tilized and  the  untreated  peas  (as  manifested  by  periodical  analyses 
of  soil  extracts  prepared  from  carefully  taken  representative  soil 
samples),  samples,  taken  as  previously  described,  were  drawn  and 
analyzed  on  September  3,  after  the  plots  had  been  prepared  but 
before  the  superphosphate  had  been  applied,  and  subsequently  as  the 
data  in  Table  V  show.     (See  also  graphs  in  figs.  3  and  4.) 

TABLE  V 
Periodic  Laboratory  Data  on  Field  Plot  Soils 

Conductivity 
Measurements. 

Specific  Determinations   of   Plant   Food   Ions    (p.  p.   m.   dry  soil) 

Resistance  , A N 

Dates  of  in  Ohms  Ca-Ion  Mg-Ion  K-Ion  N03-Ion  PO^Ion 

Soils  1  21212121  2  12 

9-3-19  3000  3000  61  61  45  45  49  49  150  150  5.2  5.2 

11-3-19  2560  1382  75  153  46  136  45  99  133  177  5.2  19.5 

1-20-20  2430  1497  54  134  42  109  51  83  155  177  4.6  8.7 

2-21-20  2970  1855  50  160  34  106  47  83  133  133  1.5  4.5 

3-27-20  2495  1792  56  167  52  113  54  83  49  35  2.3  3.7 

4-26-20  3965  2162  26  96  20  74  32  58  0  5  2.0  3.0 

5-24-20  3258  1895  46  150  37  93  36  54  10  5  2.3  2.8 

In  all  cases  No.  1  =  check  plots  and  No.  2  =:  phosphate-treated  plots. 

As  the  rainfall  during  the  year  1919-1920  was  below  the  normal 
average  for  Marin  Meadows  Ranch,*  and  as  the  growth  of  the  peas 


*  The  annual  rainfall  data  for  the  past  seven  years,  September  1  to  Septem- 
ber 1,  follows : 

1913-1914  35.79  inches 

1914-1915  32.99  inches 

1915-1916  27.31  inches 

1916-1917  14.19  inches 

1917-1918  9.20  inches 

1918-1919  17.99  inches 

1919-1920  11.39  inches 


1922]  Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas  353 

was  so  largely  dependent  upon  this  factor,  it  was  not  thought  always 
desirable  to  draw  soil  samples  at  exactly  four-week  intervals.  The 
following  brief  summary  shows  the  sampling  dates  and  correlates  with 
these  the  condition  of  the  peas  at  those  times. 

September  3,  1919:  First  samples  drawn.  Plots  staked  out  but  no  fertilizers 
yet  applied. 

November  3,  1919:  First  sampling  since  planting.  As  less  than  0.3  of  an 
inch  of  rain  had  fallen  since  planting,  but  few  of  the  seeds  had  sprouted. 

January  20,  1920:  The  peas  were  2  to  3  inches  high  and  a  good  stand  had 
been  secured.  Over  4  inches  of  rain  had  fallen  since  last  sampling,  but 
the  nights  were  cold  (often  below  freezing),  and  the  days  were  usually 
cloudy  and  cold. 

February  21,  1920:  Less  than  one  inch  of  rain  had  fallen  since  January 
20.  The  soil  was  very  dry  (moisture  determinations  showed  but  27%  in 
the  surface  soil  and  42%  in  the  subsoil).  The  plants  had  grown  but  an 
inch  or  two  during  the  month  and  were  often  more  or  less  wilted  during 
the  middle  of  the  day.  The  nights  were  cold.  Poor  conditions  for  growth. 
There  was  no  difference  between  the  checks  and  the  phosphate-treated  plots. 

March  27,  1920:  The  plants  were  looking  well.  About  3  inches  of  rain 
had  fallen  since  last  sampling.  The  vines  on  the  cheek  plots  were  6  to 
8  inches  high  while  those  on  the  phosphate-treated  plots  were  10  to  12  inches 
high.     The  lime-treated  plots  showed  no  improvement  over  the  checks. 

April  26,  1920:  The  plants  were  looking  fairly  well,  although  little  rain 
had  been  recorded  during  the  month  past.  The  vines  were  covered  with 
blossoms  and  filling  pods.  There  was  a  noticeable  difference  in  favor  of 
phosphate-treated  plots  although  the  lime-treated  plots  showed  no  gain. 

May  24,  1920:  Peas  about  ready  to  cut.  Vines  turning  yellow;  pods  well 
filled  and  dry.  The  soil  had  dried  out  and  was  very  parched  and  hard. 
This  was  the  last  date  of  sampling. 

The  plots  were  harvested  June  3.  The  yields  obtained  are  shown 
in  Table  VI. 

TABLE  VI 
Plot  Yields 

Gross  Weights, 

Dry  Peas  and  Net  Weights, 

Vines  Dry  Peas 

i ' v  , * > 

lbs.  per  lbs.  per 

lbs.  acre  lbs.  acre 

Average  yield  per  y10  acre  plot  (checks)....      627  6,270  153  1,530 

Average  yield  per  y10  acre  plot  (superphos- 
phate)          820  8,200  200  2,000 

Average  yield  per  y5  acre  plot  (cheeks)....  1,010  5,050  340  1,700 

Average  yield  per  %  acre  plot  (sugar  beet 

lime)    1,090  5,450  340  1,700 

Average  yield   per    %    acre   plot    (ground 

limestone)   1,090  5,450  330  1,650 

It  will  be  seen  that  liming  to  neutrality  had  no  effect  upon  yields. 
This  is  in  accordance  with  former  field  observations  on  this  soil.  A 
more  extended  discussion  of  the  effects  of  the  application  of  lime 


354 


University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 


will  be  given  later  in  connection  with  results  secured  in  the  green- 
house where  moisture  conditions  were  optimum  and  where  a  more 
careful  chemical  control  was  possible.  The  superphosphate  treatment 
increased  the  yield  of  peas  by  approximately  25  per  cent.  This 
increase  about  paid  for  the  treatment,  and  a  future  residual  effect 
may  be  expected.  Possibly  a  larger  amount  of  superphosphate  would 
have  given  higher  yields,  for  much  was  lost  due  to  reversion  (see 
below). 


•   300 

Parts  per  million  of  soil 

o                       o 

o                       o 

5^ 

^^*<L 

^ 

t?Q*-~ 

—        ~ 

\ 

__———-" 

K ^= 

■ ■ Mo 

\ 

:=T^: 

5>^*4 

=55 

^-^r-- 

^Oy 

Dates  sampled. 

Fig.  3. — Water-soluble  materials  dissolved  from  unfertilized  plot  soils  carrying 
pea  crop. 

As  has  been  mentioned,  the  rainfall  was  subnormal  throughout  the 
entire  growing  period.  That  the  low  yields  secured  on  both  treated 
and  untreated  plots  were  attributable  in  large  part  to  a  lack  of  water 
will  be  shown  by  the  following  test.  Four  approximately  50-foot  rows 
(two  in  a  phosphate  plot  and  two  in  a  check  plot)  were  chosen  at 
random  and  regularly  irrigated*  for  a  period  of  several  weeks 
during  the  months  of  February  and  March.  Rapid  growth  and  great 
improvement  over  those  plants  not  so  treated  was  observed.  As  heavy 
rains  fell  during  the  latter  part  of  March,  irrigating  was  discontinued. 
The  beneficial  results  of  these  few  applications  of  water  during  the 
early  stages  of  growth  were,  however,  noticeable  up  to  the  time  of 
harvesting. 


*  Water  hauled  in  a  tank  wagon. 


1922] 


Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas 


355 


The  curves  presented  in  figures  3  and  4  show  graphically  the  rise 
and  fall  in  concentration  of  the  soil  solution  under  the  growing  crop.  In 
studying  these  graphs  it  should  be  remembered  that  the  superphosphate 
was  applied  between  September  3  and  November  3  (see  figure  4),  and 
that  the  plants  were  absorbing  nutrients  most  vigorously  during  the 
months  of  March  and  April.  We  note  first  that  much  greater  con- 
centrations of  salts  prevail  throughout  the  entire  period  within  the 
soils  of  the  fertilized  plots.     This  is  clearly  depicted  by  the  solid  line 


Dates  sampled. 

Fig.  4. — Water-soluble  materials  dissolved  from  phosphate-treated  plot  soils 
carrying  pea  crop. 

representing  one-tenth  of  the  specific  resistance  in  ohms.  That  this 
increased  concentration  is  due  in  large  part  not  to  the  superphosphate, 
but  to  the  increased  solubility  of  other  ions  caused  by  it  within  the 
soil  itself,  is  strikingly  shown  by  the  Mg  and  K  graphs.  This  doubt- 
less accounts  largely  for  the  greater  yields  obtained  on  the  phosphate 
plots,  for  where  water  is  limited,  Morgan37  has  shown  that  transpira- 
tion is  necessarily  less,  and  that  the  enhancing  effect  of  fertilizers  is 
relatively  greatly  increased.  He  states,  "All  fertilizers,  both  mineral 
and  nitrogenous,  have  greatly  decreased  in  their  relative  efficiency  fol- 
lowing an  increase  in  soil  moisture.  The  decrease  is  consistent."  It 
is  further  a  well  established  physiological  fact  that  water  is  greatly 
economized  by  increasing  the  plant's  supply  of  mineral  salts  (see 
Russel,40  pages  29,  30). 


356  University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 

Taking  up  the  ions  separately,  we  note  that  phosphate  applications 
have  but  slightly  affected  nitrate  formation.  This  is  doubtless  due 
to  excessive  soil  acidity  which  dominates  nitrification  within  this  soil. 

The  yields  show  that  soluble  nitrogen  is  here  more  than  adequate 
for  peas.  The  amounts  of  potassium  and  magnesium,  soluble  in  water, 
in  this  heavy  clay  soil,  have  been  almost  doubled  throughout  the 
entire  growing  period  by  the  initial  acid-phosphate  application.  That 
the  gypsum  present  in  the  superphosphate  is  largely  responsible  for 
this  increase  is  shown  by  results  secured  in  the  more  carefully  con- 
trolled greenhouse  experiment  (see  McCool  and  Millar33  in  this  con- 
nection). As  would  be  expected,  both  water-soluble  calcium  and 
phosphorus  have  been  somewhat  increased  in  the  soils  of  those  plots 
receiving  the  soluble  phosphate  treatments. 

Chlorides  and  sulfates  were  periodically  determined.  As  these  ions 
were  always  present  in  great  excess,  however,  they  have  not  been 
included  in  Table  V  nor  in  the  graphs,  but  have  been  more  properly 
figured  as  the  sodium  salts  (white  alkali),  and  appear  in  Table  VII. 
An  idea  has  prevailed  in  the  past  that  occasional  increases  in  the 
amount  of  alkali  present  may  have  been  responsible  for  crop  failures. 

TABLE  VII 
Periodical  Determination  of  White  Alkali  in  Plot  Soils 

Date                                                                            %  NaCl  %  NasSO*     ' 

September  3,  1919  0.018  0.066 

November  3,  1919 025 

January  20,  1920  023  .066 

February  21,  1920  017  .067 

March  27,  1920  032  .060 

April  26,  1920  017  .050 

May  24,  1920  020  .100 

While  the  percentages  of  alkali  here  noted  are  doubtless  innocuous 
if  optimum  moisture  conditions  exist,  it  is  conceivable,  as  before  stated, 
that  at  times  of  unusual  drought,  plants  may  suffer  in  the  more  con- 
centrated soil  solution  that  results,  and,  while  a  lack  of  water  is 
directly  responsible  for  this  condition,  alkali  salts  may  well  be  con- 
sidered an  important  indirect  or  contributing  factor. 

Other  toxic  compounds,  as  ferrous  iron*  or  soluble  aluminum  salts, 
here  appealed  to  the  writer  as  being  possible  causes  of  infertility. 
We  were,  however,  unable  to  secure  a  positive  test  for  ferrous  iron 
in  the  surface  soil.    Special  samples  were  taken  for  these  tests,  every 

*  Certain  heavy  soils  of  the  Transvaal  have  been  shown  by  Watt46  to  have  been 
rendered  unproductive  by  accumulations  of  ferrous  salts. 


1922]  Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas  357 

precaution  being  used  to  avoid  oxidation  in  transit.  On  the  other 
hand,  water-soluble  aluminum  was  usually  found.  Large  numbers 
of  determinations  showed  it  to  be  present  to  the  extent  of  12  to  15  parts 
per  millon  in  the  surface  soil,  while  approximately  twice  these  amounts 
were  found  in  the  subsoil. 

The  considerable  literature  upon  the  subject  of  aluminum  toxicity 
has  been  notably  extended  during  the  past  two  or  three  years  by  the 
careful  work  of  Hartwell  and  Pember,17'  18  Conner,9  Ames  and  Schol- 
lenberger,2  and  Miyake.35  The  first-mentioned  investigators  have 
definitely  shown  that  soluble  aluminum  compounds  exist  in  toxic  con- 
centrations in  certain  acid  soils;  that  plants  differ  in  their  powers  of 
resistance  to  soluble  aluminum  ;  and  that  such  conditions  may  be  readily 
ameliorated  by  applications  of  any  substance  which  will  precipitate 
aluminum-ion.  From  data  furnished  by  Hartwell  and  Pember18  (page 
266),  it  is  possible  to  calculate  the  concentration  of  soluble  aluminum 
present  in  the  acid  soils  upon  which  they  experimented.  This  was 
found  to  be  approximately  77  parts  of  A1203  or  41  parts  of  soluble 
aluminum  per  one  million  parts  of  dry  soil.  They  extracted  using 
slightly  different  proportions  (about  1  to  3)  of  soil  and  water  than 
did  the  writer,  but  the  results  should  be  fairly  comparable.  They 
furthermore  found  that  at  least  15  p.  p.  m.  of  aluminum  in  solution 
cultures  with  growing  plants  were  required  to  produce  signs  of  tox- 
icity. In  the  light  of  these  results,  it  would  appear  somewhat  doubt- 
ful whether  the  relatively  small  quantities  (12  to  15  p.  p.  m.  of 
aluminum)  found  in  the  soil  of  the  Marin  Meadows  Ranch  could  be 
entirely  responsible  for  the  seriously  depleted  yields.  The  other 
authors  cited  in  this  connection  have  shown  that  amounts  of  aluminum 
greatly  in  excess  of  15  p.  p.  m.  of  soil  are  necessary  to  render  con- 
ditions toxic  for  crop  plants  in  soils ;  and,  finally,  the  plants  in  our 
own  untreated  pots,  in  which  this  soil  was  used  without  drainage,  gave 
no  indications  of  aluminum-poisoning. 

To  sum  up  briefly  the  points  brought  out  by  the  field  plot  experi- 
ment, we  may  conclude  with  reasonable  certainty  that,  during  the  past 
season  at  least,  water  has  been  the  limiting  factor  in  crop  production ; 
that  a  one-ton  application  of  superphosphate  in  absence  of  irrigation 
has  increased  the  yield  of  peas  by  approximately  25  per  cent;  that 
liming  to  neutrality  had  practically  no  effect  upon  yield,  due  possibly 
to  delayed  reaction  on  account  of  paucity  of  rainfall ;  and,  finally,  that 
inorganic  toxins,  as  alkali,  ferrous  iron,  and  aluminum  salts,  are 
probably  at  present  not  directly  responsible  for  lack  of  productivity. 


358  University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 


THE  GKEENHOUSE  EXPERIMENTS 

While  field  trials  are  generally  considered  as  being  the  most  reliable 
method  of  solving  fertility  problems,  they  are  expensive  and  cumber- 
some, and,  as  has  already  been  shown,  should  be  executed  over  a  period 
of  years  to  allow  for  a  fair  average  of  climatic  conditions.  The  quicker, 
less  expensive,  and  more  controllable  pot  experiment,  as  carried  out 
in  a  well  equipped  greenhouse,  is  therefore  often  desirable.  Coffey 
and  Tuttle,7  Wheeler,  Brown  and  Hogensen,40  and  others  have 
compared  pot  tests  with  field  trials  and  have  shown  them  to  agree 
remarkably  well  where  certain  details  of  manipulation  are  followed. 
Furthermore,  the  ofttimes  limiting  factors  of  moisture  and  tempera- 
ture may  be  so  controlled  in  greenhouse  work  as  to  permit  of  more 
definite  conclusions  regarding  possible  plant  food  deficiencies.  In  the 
present  work,  this  method  of  experimentation  was  especially  adaptable, 
as  frequent  periodical  soil-sampling  was  required. 

The  proper  kind  and  quantity  of  fertilizer  to  apply  depend  as  much 
upon  the  total  effect  produced  within  the  soil  solution  as  they  do  upon 
the  element  or  elements  directly  supplied,  for  many  of  the  changes 
induced  may  be  indirect.  For  instance,  sodium  nitrate,  so  widely  used 
as  a  source  of  available  nitrogen/  may  so  deflocculate  a  heavy  soil  as  to 
render  it  non-productive.  Much  information  is  at  present  available 
in  agricultural  literature  on  the  effects  of  additions  of  fertilizer  salts 
and  other  chemical  compounds  upon  the  solubility  of  soil  constituents. 
While  a  large  portion  of  these  data  have  been  secured  by  subjecting  the 
soils  studied  to  artificial  laboratory  conditions,  far  removed  from  those 
actually  obtaining  in  the  field,  nevertheless  many  of  them  have  a 
sufficient  bearing  upon  the  present  work  to  necessitate  reviewing. 
More  than  seventy-  articles  were  read  in  this  connection.  However,  as 
comprehensive  references  to  the  literature  accompany  the  papers  of 
Greaves  and  Carter,13  Spurway,43  and  Maclntire,31  it  was  thought  best 
not  to  burden  the  reader  with  an  extended  review,  very  little  of  which 
could  be  directly  compared  with  data  to  be  subsequently  presented, 
but  rather  to  give  a  brief  discussion  of  the  work. as  a  whole,  noting 
the  points  in  agreement  as  well  as  those  at  variance  with  the  results 
hereafter  given. 

The  chief  impression  made  upon  the  reviewer  of  the  literature 
within  this  field  is  the  dissimilarity  and  often  contradictory  nature  of 
results  reported.  For  instance,  certain  writers  have  shown  that  addi- 
tions of  sodium  nitrate  to  soils  greatly  enhance  phosphate  availability, 


1922]  Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas  359 

while  a  like  number  may  easily  be  found  who  claim  that  sodium  nitrate 
inhibits  the  solution  of  phosphates  in  soils.  Similar  differences  of 
opinion  exist  regarding  the  effects  of  lime  and  gypsum  upon  the 
solubility  of  soil  potash.  An  able  discussion  of  such  discrepancies, 
at  least  in  so  far  as  the  effects  of  calcium  carbonate  and  gypsum  upon 
soil  potassium  are  concerned,  is  given  by  Lipman  and  Gericke.29  These 
writers  attribute  unlike  and  contradictory  results  to  variations  in  the 
nature  of  the  mineral  content  of  the  soils  from  different  localities. 
The  linkages  binding  potassium  within  the  intricate  silicate  molecules 
doubtless  vary  greatly  with  different  mineral  complexes,  the  potassium 
being  much  more  easily  replaced  by  calcium,  sodium,  or  other  metallic 
ions  in  some  instances  than  in  others.  As  this  might  equally  well 
apply  to  all  the  elements  ordinarily  met  with  in  soils,  one  could  hardly 
expect  similar  results  to  be  obtained  in  all  cases  and  for  all  elements. 
In  fact,  Lipman  and  Gericke,29  Spurway,43  Christie  and  Martin,0  and 
many  others  give  data  which  conclusively  show  that  applications  of 
the  same  salts  in  similar  amounts  react  differently  in  different  soils. 
Another  factor  which  doubtless  also  plays  a  part  is  soil  texture.  The 
fine  clays  and  clay  loams  presenting  many  times  the  internal  surface 
found  in  the  coarser  silts  and  sands,  should,  and  usually  do,  yield  more 
material  to  solution.    This  is  probably  largely  a  mechanical  factor. 

Taking  the  recorded  data  on  this  subject  by  and  large,  the  following 
statements  seem  to  be  justified  in  a  majority  of  cases.  The  normal 
sulfates  and  chlorides  of  calcium,  magnesium,  sodium,  and  ammonium, 
may  enhance  the  solubility  of  soil  potassium  and  soil  phosphorus, 
although  the  acid  salts  act  much  more  strongly,  especially  in  the  case  of 
the  latter  element.  Nitrates  act  erratically,  but  we  are  fairly  safe 
in  saying  that  they  usually  slightly  increase  soil  potash  solubility, 
and  exert  little  effect  on  soil  phosphorus,  although  we  know  that  the 
calcium  phosphates  are  much  more  soluble  in  solutions  of  nitrates  than 
are  the  iron  and  aluminum  phosphates.  The  addition  of  calcium  oxide 
usually  increases  potash  solubility  while  the  carbonate  often  has  no 
direct  effect.  Phosphate  solubility  is  usually  depressed  by  lime  appli- 
cations, although  this  is  not  universally  the  case  with  quicklime,  while 
the  sulfates  of  the  heavy  metals  often  greatly  increase  it.  Many 
writers  have  also  shown  that,  under  certain  conditions,  the  soil  bac- 
teria, especially  the  nitrifiers,  exert  a  decided  solvent  action  upon  the 
insoluble  phosphates  of  both  soils  and  fertilizers. 


360 


University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 


Objects  of  the  Pot  Experiments 

The  objects  of  the  pot  experiments  hereafter  reported  were:  (1) 
so  far  as  possible  to  eliminate  climate,  especially  moisture,  as  a  factor 
in  crop  production  upon  the  soil  studied,  and  to  maintain  throughout 
the  growth  period  as  nearly  optimum  conditions  as  possible;  (2)  to 
note  the  effects  upon  the  growth  of  the  pea  plants,  and  upon  the  final 
yields  of  dried  peas,  of  additions  of  the  several  fertilizers  and  soil 
amendments  supplied;  (3)  to  find  whether  or  not  such  applications  of 
chemical  compounds  influence  the  solubilities  of  the  soil's  constituents 
as  manifested  by  periodical  extractions  of  both  planted  and  fallowed 
soils  with  distilled  water;  (4)  to  ascertain  the  effect  of  soluble  salt 
applications  upon  the  nodule  formation  of  peas  within  this  acid  soil ; 
(5)  to  ascertain  whether  or  not  soil  toxins  of  any  kind  were  inhibiting 
normal  growth. 


Dates  sampled. 

Fig.  5. — Water-soluble  materials  dissolved  from  cropped  check  pot  soils  (no 
fertilization). 


1922] 


Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas 


361 


Treatments  Employed 

The  experiments  were  carried  out  in  a  well  regulated  greenhouse. 
The  pots  used  were  5-gallon  glazed  earthenware  crocks  about  12  inches 
in  diameter  and  11  inches  deep.  No  holes  were  provided  for  drainage 
as  it  was  desired  that  no  soluble  constituents  be  lost  during  the  growth 
of  the  crops.    The  pots  were  weighed,  and  water  added  to  optimum  at 


Dates  sampled. 

Fig.  6. — Water-soluble  materials  dissolved  fi 
soils. 


inn 


cropped  gypsum-treated  pot 


each  irrigation.  The  soil  was  procured  during  the  month  of  August 
from  the  field  plots  above  described,  6  two-bushel  sacks  of  surface  soil 
being  taken  from  each  of  the  6  one-tenth  acre  plots.  It  was  air-dry 
and  dusty  to  a  depth  of  approximately  6  inches.  When  received  at 
the  greenhouse,  it  was  thoroughly  mixed  by  being  shoveled  over  five 
times  and  twice  screened  (one-fourth  inch  mesh)  to  remove  the  larger 
clods.  Thirteen  kilograms  were  then  weighed  into  each  of  64  pots, 
thus  providing  eight  pots  for  each  of  the  eight  different  treatments  to 
be  tested.    The  additions  were  made  as  follows: 


362 


University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 


Pots  1-  8:  Checks.    No  additions. 

Pots  9-16:  Gypsum  at  the  rate  of  1  T.  per  acre  (20  g.  per  pot). 

Pots  17-24:  CaC03  at  the  rate  of  8  T.  per  acre  (160  g.  per  pot). 

Pots  25-32:  Superphosphate  at  the  rate  of  1  T.  per  acre  (20  g.  per  pot). 

Pots  33-40:  NaN03  at  the  rate  of  500  lbs.  per  acre  (5  g.  per  pot). 

Pots  41-48:  K2S04  at  the  rate  of  500  lbs.  per  acre  (5  g.  per  pot). 

Pots  49-56:  Super.  (1  T.  per  a.)  and  K,S04  (500  lbs.  per  a.). 

Pots  57-64:  Super.  (1  T.  per  a.)  and  CaCOs  (8  T.  per  a.). 

As  will  be  observed,  the  applications  here  made  were  in  all  eases 
consistent  with  good  field  practice.  The  amounts  of  salts  (dry)  as 
indicated  were  thoroughly  mixed  into  the  surface  six  inches  of  soil 


600 


500 


400 


300 


e3 

ft 


200 


100 


Dates  sampled. 

Fig.    7. — Water-soluble    materials    dissolved   from    cropped    calcium-carbonate- 
treated  pot  soils. 


1922]  Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas  363 

in  each  pot,  after  which  the  soils  were  settled  into  place  by  an  irrigation 
calculated  to  be  optimum  (one-half  total  moisture  holding  capacity). 
The  pots  were  then  allowed  to  stand  for  one  week  before  planting.  The 
salts  applied  were  "Bakers  C.  P.  Analyzed  Chemicals"  in  all  cases 
except  the  superphosphate,  which  was  the  same  as  that  used  in  the 
field  plot  experiments.  At  the  same  time,  a  set  of  six  pots  of  the  soil, 
which  were  to  be  kept  fallow  (no  crop)  were  set  up.  The  first  six, 
single-salt  treatments  only  were  here  employed.  These  fallowed  pots 
were  subsequently  treated  in  exactly  the  same  way  as  the  cropped  pots. 

The  peas  (Horseford's  Market  Garden  variety)  were  sown  on 
November  10,  1919 ;  eight  uniform  seeds  to  the  pot.  A  good  stand  was 
obtained.  When  the  plants  were  about  three  inches  high,  they  were 
thinned  to  four  per  pot.  When  6  to  8  inches  high,  the  peas  were 
trellised,  using  split  laths  and  string.  The  floor  plan  of  the  green- 
house indicating  the  arrangement  of  the  benches  and  the  pots  is  shown 
in  figure  2.  As  the  plants  grew  taller  and  shading  was  evident  at 
certain  periods  during  the  day,  the  practice  of  changing  the  pots  from 
one  bench  to  the  other  each  week  at  the  time  of  irrigation  was  adopted. 

As  one  of  the  objects  of  the  work  was  to  ascertain  the  effects  of  the 
several  salt  applications  upon  soil-mineral  solubility,  at  approximately 
four-week  intervals  samples  of  the  cropped  soils  were  withdrawn  from 
the  pots  and  analyses  made  in  accordance  with  the  detailed  methods 
previously  given.  The  results  of  this  work  appear  in  Table  VIII  and, 
for  convenience,  are  graphically  shown  in  figures  5  to  19.  It  had  been 
planned  also  to  extract  and  analyze  the  similarly  treated  fallowed 
soils  each  month,  but,  as  the  two  series  will  be  shown  to  be  hardly  com- 
parable, and  as  time  for  this  large  amount  of  analytical  work  was 
wanting,  the  uncropped  soils  were  analyzed  but  four  times  during  the 
experiment  (during  October,  November,  January,  and  April).  The 
results  of  these  analyses  appear  in  Table  IX. 

After  thinning,  and  when  the  plants  had  reached  a  height  of  6  or  7 
inches,  some  trouble  was  experienced  with  mice.  In  eight  or  ten  of  the 
pots,  one  or  two  of  the  plants  were  destroyed.  This  difficulty  was 
quickly  overcome,  but  not  before  some  damage  had  been  done.  For 
this  reason,  in  Table  X,  only  six  pots  (out  of  the  eight  of  each  treat- 
ment) giving  the  highest  yields  per  pot,  and  having  four  plants  each, 
have  been  used  in  computing  statistically  the  final  yields  obtained, 
although  the  yields  in  all  of  the  pots  are  given.* 


*  As  stated  in  the  table,  a  star   (*)   marks  those  figures  omitted  from  the 
averages.     The  data,  when  plotted,  gave  uniform  frequency  curves. 


364  University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 


TABLE  VIII 

Periodic  Determinations  on 

Cropped,  Pot  Soils 

Treatment 
Number 

Dates   of   Sampling   Soils 

10-15-19 

11-20-19 

12-18-19 

1-19-20 

2-20-20 

3-20-20 

Acidity  expressed 

inPH 

1 

4.46 

4.51 

4.50 

4.48 

4.46 

4.71 

2 

4.46 

4.55 

4.58 

4.50 

4.51 

4.73 

3 

4.46 

7.20 

7.20 

7.39 

7.34 

7.25 

4 

4.46 

4.67 

4.62 

4.62 

4.60 

4.71 

5 

4.46 

4.67 

4.72 

4.53 

4.63 

4.88 

6 

4.46 

4.67 

4.68 

4.67 

4.67 

4.88 

7 

4.46 

4.63 

4.63 

4.63 

4.65 

4.80 

8 

4.46 

7.30 
Specific 

7.33 
:  Eesistance 

7.46 
in  Ohms 

7.42 

7.33 

1 

3,000 

2,381 

2,515 

2,752 

3,053 

2,726 

2 

3,000 

1,498 

1,568 

1,517 

1,728 

1,402 

3 

3,000 

1,420 

1,331 

1,325 

1,357 

1,261 

4 

3,000 

1,280 

1,568 

1,856 

2,022 

1,587 

5 

3,000 

2,112 

2,029 

2,131 

2,374 

2,302 

6 

3,000 

2,131 

2,054 

2,400 

2,509 

2,118 

7 

3,000 

1,286 

1,472 

1,523 

1,702 

1,382 

8 

3,000 

1,171 

1,133 

998 

1,088 

1,018 

Calcium 

-ion,  parts  per  million 

1 

60 

49 

35 

34 

41 

25 

2 

60 

269 

262 

150 

133 

169 

3 

60 

279 

319 

309 

295 

350 

4 

60 

131 

136 

104 

88 

128 

5 

60 

59 

59 

50 

43 

48 

6 

60 

169 

71 

55 

52 

56 

7 

60 

160 

150 

121 

102 

169 

8 

60 

387 

430 

428 

434 

500 

Magnesium-ion,  parts 

per  million 

1 

45 

46 

40 

37 

30 

29 

2 

45 

105 

109 

120 

107 

125 

3 

45 

110 

121 

117 

116 

130 

4 

45 

110 

106 

79 

78 

102 

5 

45 

55 

53 

48 

46 

38 

6 

45 

70 

67 

56 

48 

55 

7 

45 

133 

125 

98 

86 

127 

8 

45 

145 

147 

144 

150 

154- 

Potassium-ion,  parts 

per  million 

1 

50 

58 

54 

50 

39 

35 

2 

50 

75 

84 

80 

75 

60 

3 

50 

69 

64 

65 

60 

63 

4 

50 

87 

81 

68 

51 

61 

5 

'50 

65 

66 

58 

41 

37 

6 

50 

88 

86 

75 

58 

63 

7 

50* 

117 

117 

97 

70 

92 

8 

50 

75 

69 

74 

56 

65 

1922] 


Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas 


365 


TABLE  VIII—  (Continued) 

Dates   of    Sampling    Soils 


Treatment 
Number 

10-15-19 

11-20-19 

A 

12-18-19         1 

-19-20 

3-20-20 

3-20-20 

Phosphate 

ion,  parts  per  million 

1 

5.2 

3.7 

4.5 

2.3 

3.5 

2.1 

2 

5.2 

6.2 

5.6 

4.0 

4.0 

3.4 

3 

5.2 

6.2 

4.7 

4.5 

4.1 

5.4 

4 

5.2 

8.5 

6.8 

8.4 

7.2 

4.1 

5 

5.2 

5.6 

5.9 

4.1 

4.3 

2.3 

6 

5.2 

5.6 

5.6 

4.7 

4.5 

2.0 

7 

5.2 

7.4 

7.0 

7.4 

6.9 

3.2 

8 

5.2 

7.6 

6.7 

7.8 

7.0 

5.6 

Nitrate-ion,  parts  per 

million 

1 

150 

89 

267 

204 

35 

5 

2 

150 

80 

239 

213 

44 

0 

3 

150 

338 

621 

532 

266 

84 

4 

150 

156 

221 

177 

27 

0 

5 

150 

488 

488 

400 

177 

30 

6 

150 

178 

266 

177 

44 

5 

7 

150 

156 

266 

177 

40 

7 

8 

150 

196 

485 

443 

266 

156 

300 


200 


100 


- 

—  \ 

y 

X 

\ 

\ 

/  / 

JT"^-- 

._.ZX^ 

f 

TO* 

Dates  sampled. 

Fig.  8. — Water-soluble  materials  dissolved  from  cropped  superphosphate-treated 
pot  soils. 


3(56  University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 

TABLE  IX 
Periodic  Determinations  on  Fallowed,  Pot  Soils 

Dates   of    Sampling    Soils 


.  reatment 
Number 

10-15-19 

A 

11-20-19 

1-25-20 

4-1-20 

Acidi' 

ty  expressed  in 

PH 

1 

4.46 

4.50 

4.43 

4.32 

2 

4.46 

4.55 

4.50 

4.38 

3 

4.46 

7.20 

7.17 

7.17 

4 

4.46 

4.67 

4.46 

4.46 

5 

4.46 

4.67 

4.45 

4.43 

6 

4.46 

4.67 

4.40 

4.38 

Specific 

Resistance  in 

Ohms 

1 

3,000 

2,380 

lost 

2,048 

2 

3,000 

1,498 

lost 

1,338 

3 

3,000 

1,420 

lost 

1,011 

4 

3,000 

1,280 

lost 

2,180 

5 

3,000 

2,112 

lost 

1,587 

6 

3,000 

2,131 

lost 

1,754 

Calcium- 

ion,  parts  per  million 

1 

60 

49 

72 

81 

2 

60 

269 

250 

209 

3 

60 

279 

514 

512 

4 

60 

131 

112 

99 

5 

60 

59 

104 

100 

6 

60 

169 

128 

104 

Magnesium-ion,  parts  pei 

•  million 

1 

45 

46 

67 

80 

2 

45 

105 

147 

161 

3 

45 

110 

144 

157 

4 

45 

110 

105 

105 

5 

45 

55 

86 

96 

6 

45 

70 

67 

98 

Potassium-ion,  parts  per 

million 

1 

50 

58 

58 

59 

2 

50 

75 

86 

84 

3 

50 

69 

65 

59 

4 

50 

87 

81 

73 

5 

50 

65 

68 

72 

6 

50 

88 

86 

96 

Phosphate 

;-ion,  parts  per 

million 

1 

5.2 

3.7 

3.7 

2.3 

2 

5.2 

6.2 

4.1 

2.4 

3 

5.2 

6.2 

4.5 

4.3 

4 

5.2 

8.5 

8.4 

8.8 

5 

5.2 

5.6 

5.6 

4.1 

6 

5.2 

5.6 

4.7 

2.3 

Nitrate-i 

on,  parts  per  million 

1 

150 

89 

400 

575 

2 

150 

80 

756 

708 

3 

150 

338 

1,264 

1,106 

4 

150 

156 

550 

496 

5 

150 

488 

421 

940 

6 

150 

178 

355 

575 

1922]  Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas  367 

Crop  Yields 

The  effects  of  the  several  soil  treatments  upon  crop  yields  will  first 
be  considered.  Table  X  presents  this  data  while  a  chart  showing 
graphically  the  comparative  yields  of  both  total  dry  matter  and 
cured  peas  appears  in  figure  20.  The  "plus  or  minus"  variability 
factors  as  shown  in  figure  20  are  obtained  by  multiplying  the  "prob- 
able error  of  the  mean"  in  each  case  (Table  X)  by  three,  thus  insuring 
practically  a  thirty  to  one  chance  that,  in  case  of  repetition,  the  new 
average  yields  found  will  fall  within  these  limits.  Those  figures  also 
help  us  in  determining  approximately*  whether  or  not  significant 
differences  in  yields  are  shown  between  treatments,  t 

The  most  notable  fact  impressed  upon  one  who  has  carefully  fol- 
lowed both  the  field  and  the  greenhouse  experiments  is  that  the  plants 
grown  in  the  greenhouse  under  nearly  ideal  climatic  conditions  grew 
to  at  least  twice  the  size  and  probably,  plant  for  plant,  produced  nearly 
twice  as  many  peas  as  those  grown  in  the  field  at  the  Marin  Meadows 
Ranch.  Although  the  crop  on  the  field  plots  was  above  the  average, 
the  individual  plants  were  small  in  comparison  with  any  (checks  in- 
cluded) grown  inside.  That  water  has  been  one  of  the  important  limit- 
ing factors  in  the  field  during  the  past  season  can  hardly  be  ques- 
tioned. 

The  second  point  to  be  noticed  is  the  comparatively  small  increase 
over  the  check  pots  due  to  any  of  the  fertilizer  applications.  One  would 
certainly  expect  a  soil  so  low  in  soluble  phosphorous  or  so  acid  in 
reaction  to  respond  greatly  to  applications  of  either  soluble  phosphates 
or  lime,  and  certainly  where  both  were  used.  But  no  such  large  increases 
are  apparent.    It  is  true  that  enhanced  yields  follow  the  application  of 


*  The  exact  method  of  determining  whether  or  not  a  difference  is  significant 
is  to  take  the  square  root  of  the  sum  of  the  squares  of  the  two  probable  errors 
of  the  two  means,  multiply  the  resulting  figure  by  3  and  note  whether  or  not 
the  product  is  larger  or  smaller  than  the  subtracted  difference  between  the  two 
means.  In  case  it  is  smaller,  it  is  safe  to  conclude  that  the  difference  between 
the  two  means  is  significant,  taking  a  30  to  1  chance  of  securing  a  similar  result 
upon  repetition.  For  example,  let  us  compare  the  average  yield  of  total  dry 
matter  secured  in  the  check  pots  with  that  where  gypsum  was  applied,  and 
find  whether  or  not  gypsum  actually  increased  yields: 

59.5  ±  0.9  =  mean  of  gypsum  pots. 
51.4  ±  1.3  =  mean  of  check  pots. 


8.1  ±  V  0.92  +  1.32  X  3 
=  8.1  ±  V  2.50  X  3 
=  8.1  ±4.6 
As  4.6  is  much  less  than  8.1,  we  are  safe  in  concluding  that  there  is  a  significant 
difference  shown  here  between  the  means,  and  that  the  application  of  gypsum  did 
actually  slightly  increase  yields. 

t  The  scale  to  the  left  of  fig.  20  should  be  used  in  this  connection. 


368 


University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 


TABLE  X 

Yields  of  Peas  in  Greenhouse  Pot  Experiment 
Treatment  No.  1    (Checks) 


Pot  Number 

Total  Dry  Weights 

Peas  in  Pods 

Shelled  Peas 

1 

53.6 

37.1 

29.7 

2 

45.1* 

28.4* 

21.1* 

3 

58.6 

37.7 

30.9 

4 

53.6 

34.9 

28.9 

5 

50.7* 

38.6* 

31.5* 

6 

51.0 

34.5 

28.0 

7 

44.2 

33.9 

26.1 

8 

47.2 

34.1 

28.0 

Mean 

51.4+1.3 

35.4±0.4 

28.6±0.4 

Std.  Dev. 

4.7±1.4 

1.5±0.4 

1.5±0.4 

C.  V. 

9.2±1.8% 

4.2±0.8% 

5.2±1.0% 

P.  E. 

±3.2 

±1.0 

±1.0 

Treatment  No. 

2  (Gypsum) 

Pot  Number 

Total  Dry  Weights 

Peas  in  Pods 

Shelled  Peas 

9 

53.7* 

34.3* 

25.5* 

10 

55.8 

37.3 

29.5 

11 

64.3 

37.6 

29.8 

12 

62.9 

35.6 

28.4 

13 

59.0 

33.0 

29.8 

14 

58.1 

36.7 

29.7 

15 

56.6 

33.9 

26.9 

16 

56.9* 

34.0* 

26.4* 

Mean 

59.5±0.9 

35.7±0.4 

29.0±0.3 

Std.  Dev. 

3.1±0.9 

1.7±0.5 

1.0±0.3 

C.  V. 

5.2±1.0% 

4.8±0.9% 

3.4±0.7% 

P.  E. 

±2.1 

±1.1 

±0.7 

Treatment  No.  3  (Calcium  carbonate) 

Pot  Number 

Total  Dry  Weights 

Peas  in  Pods 

Shelled  Peas 

17 

68.7* 

38.6* 

30.6* 

18 

70.5 

42.9 

34.6 

19 

70.6 

41.2 

33.6 

20 

70.2 

42.8 

36.5 

21 

67.0 

40.9 

33.3 

22 

65.0 

37.2 

31.6 

23 

69.1 

44.2 

36.6 

24 

61.3* 

36.5* 

29.2* 

Mean 

68.7±0.6 

41.5±0.6 

34.4±0.5 

Std.  Dev. 

2.1±0.6 

2.2±0.6 

1.8±0.5 

C.  V. 

3.1±0.6% 

5.3  ±1.0% 

5.2  ±1.0% 

P.  E. 

±1.4 

±1.5 

±1.2 

Treatment  No.  4  (Superphosphate  of  lime) 

Pot  Number 

Total  Dry  Weights 

Peas  in  Pods 

Shelled  Peas 

25 

58.5 

35.8 

29.7 

26 

60.4 

36.4 

29.7 

27 

56.3* 

34.2* 

27.4* 

28 

68.5 

40.8 

32.6 

*  Omitted  from  average. 


1922] 


Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas 


369 


TABLE  X- 

-(Continued) 

Pot  Number 

Total  Dry  Weights 

Peas  in  Pods 

Shelled  Peas 

29 

61.8 

36.5 

29.9 

30 

68.6 

40.0 

32.0 

31 

69.1 

37.8 

30.5 

32 

60.4* 

33.4* 

27.8* 

Mean 

64.5±1.2 

38.0±0.5 

30.7±0.3 

Std.  Dev. 

4.4±1.3 

1.9±0.5 

1.1±0.3 

C.  V. 

6.8±1.3% 

5.0±0.9% 

3.6±0.6% 

P.  E. 

±3.0 

±1.3 

±0.7 

Treatment  No.  5 

(Sodium  nitrate) 

Pot  Number 

Total  Dry  Weights 

Peas  in  Pods 

Shelled  Peas 

33 

59.2 

36.0 

28.7 

34 

59.9* 

32.1* 

24.3* 

35 

60.1 

36.9 

30.0 

36 

55.9 

33.0 

26.5 

37 

60.5 

35.2 

29.1 

38 

54.7 

33.4 

27.0 

39 

53.1* 

29.0* 

23.2* 

40 

55.0 

30.2 

25.0 

Mean 

57.6±0.7 

34.1±0.6 

27.7±0.5 

Std.  Dev. 

2.4±0.7 

2.2±0.6 

1.7±0.5 

C.  V. 

4.2±0.8% 

6.4±1.2% 

6.1±1.1% 

P.  E. 

±1.6 

±1.5 

±1.2 

Treatment  No.  6  ( 

Potassium  sulfate) 

Pot  Number 

Total  Dry  Weights 

Peas  in  Pods 

Shelled  Peas 

41 

52.8 

33.1 

26.7 

42 

54.8 

31.4 

24.8 

43 

50.0* 

29.4* 

23.6* 

44 

50.6 

33.0 

26.2 

45 

56.6 

34.4 

27.7 

46 

52.3 

31.8 

25.9 

47 

58.6 

35.6 

30.6 

48 

54.8* 

29.6* 

24.5* 

Mean 

54.3±0.7 

33.2±0.4. 

27.0±0.5 

Std.  Dev. 

2.7±0.8 

1.4±0.4 

1.8±0.5 

C.  V. 

5.0±0.9% 

4.2±0.8% 

6.6±1.2% 

P.  E. 

±1.8 

±0.9 

±1.2 

Treatment  No.  7 

(Super,  plus  K,S04) 

Pot  Number 

Total  Dry  Weights 

Peas  in  Pods 

Shelled  Peas 

49 

49.7* 

28.3* 

23.0* 

50 

47.8 

30J 

25.5 

51 

47.4* 

23.3* 

18.6* 

52 

53.5 

31.3 

25.2 

53 

57.0 

33.1 

29.1 

54 

51.6 

31.2 

26.2 

55 

56.7 

33.2 

27.4 

56 

57.4 

34.8 

29.1 

Mean 

54.0±1.0 

32.3±0.4 

27.1  ±0.4 

Std.  Dev. 

3.5±1.0 

1.6±0.5 

1.6±0.5 

C.  V. 

6.5±1.2% 

4.9±1.0% 

5.9±1.2% 

P.  E. 

±2.4 

±1.1 

±1.1 

*  Omitted  from  average. 


370 


University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 


TABLE  X— (Continued) 

Treatment  No.  8  (Super,  plus  CaC03) 


t  Number 

Total  Dry  We 

ights 

Peas  in  Pods 

Shelled  Peas 

57 

64.7 

41.0 

34.3 

58 

54.5* 

33.0* 

27.9* 

59 

62.8 

38.0 

32.4 

60 

55.9 

35.2 

30.4 

61 

54.9* 

33.0* 

28.2* 

62 

64.6 

42.7 

35.7 

63 

60.6 

39.1 

33.2 

64 

71.9 

48.2 

41.1 

Mean 

63.4± 

1.3 

40.7±1.1 

34.5±0.9 

Std.  Dev. 

4.8  ± 

1.4 

4.1±1.2 

3.3±1.0 

C.  V. 

7.5± 

1.4% 

10.1±1.8% 

9.6±1.8% 

P.  E. 

±3.2 

±2.8 

±2.12 

Dates  sampled. 

Fig.  9. — Water-soluble  materials  dissolved  from  cropped  sodium-nitrate-treated 

pot  soils. 


*  Omitted  from  average. 


1922] 


Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas 


371 


certain  of  these  compounds,  but  they  amount  to  relatively  little.  Let 
us  observe  the  chart  showing  comparative  yields  (fig.  20),  first  taking 
up  "Total  Dry  Weights"  produced.  Treatment  No.  1  (checks)  pro- 
duced lower  yields 'than  did  any  of  the  others,  yet  brief  computations 
show  that  the  differences  between  the  checks  and  treatments  6  (K2S04) 
and  7  (K2S04  +  superphosphate)  are  not  significant,  while  the  real 
difference  between  the  checks  and  5  (NaN03)  is  so  slight  (less  than  2 


Dates  sampled. 

Fig.   10.- — Water-soluble   materials   dissolved    from   cropped   potassium-sulfate- 
treated  pot  soils. 

grams)  as  to  be  well-nigh  negligible.  We  are,  however,  justified  in 
stating  that  liming  to  neutrality  did  actually  increase  the  yields  of 
peas  in  the  greenhouse  over  the  checks  by  nearly  35%  ;  that  applica- 
tions of  superphosphate,  at  the  rate  of  one  ton  per  acre,  gave  an 
increase  of  approximately  28%  ;  that  the  same  amounts  of  super- 
phosphate and  CaC03  when  used  together  increased  yields  no  more 
than  did  either  when  added  separately;  and  that  gypsum  at  the  rate 
of  one  ton  per  acre  was  about  one-half  as  effective  as  CaC03  when  the 
latter  was  used  in  sufficient  quantities  to  neutralize  soil  acidity  (8  tons 
per  acre).    It  will  be  recalled  that,  in  the  field,  superphosphate  alone 


372 


University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 


gave  increased  yields,  while  calcium  carbonate,  added  to  neutrality, 
had  little  effect.  The  comparative  solubilities  of  the  two,  water  being 
limited  in  the  field,  may  well  account  for  these  differences.  The  final 
yields  of  dry  matter  obtained,  however,  do  not  shew  the  comparative 
i-ates  of  growth  nor  do  they  reflect  the  conditions  of  the  plants  at  the 
various  monthly  periods  of  sampling.    During  the  entire  experiment 


Dates  sampled. 

Fig.  11. — Water-soluble  materials  dissolved  from  cropped  pot  soils  receiving 
both  superphosphate  and  potassium  sulfate. 

the  phosphate  treated  plants  were  apparently  far  ahead  of  all  others 
in  size,  color,  and  general  condition.  They  bloomed  and  set  pods 
at  least  a  week  before  the  other  treatments  and  matured  ten  days 
earlier  than  the  others.  The  nitrate  treated  plants  started  well 
but  soon  fell  behind.  The  lime  treated  plants  made  a  slow,  steady 
growth  from  the  start,  and,  as  will  be  seen,  gave  maximum  yields 
both  of  total  dry  matter  produced  and  of  dry  peas.  Potassium  sulfate 
wherever  applied  seemed  at  all  times  to  retard  growth.  This  may  be 
due  to  the  considerable  quantity  of  sulfate-ion  added,  as  the  soil 
already  carried  nearly  one-tenth  of  one  per  cent  sodium  sulfate. 
Gypsum  also  at  first  impeded  growth.     Figure  21  gives  one  a  good 


1922] 


Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas 


373 


idea  of  the  plants  when  the  pods  were  setting  (about  one  month 
before  harvesting).  It  serves  to  compare  the  several  treatments,  an 
average  pot  from  each  series  being  taken  in  each  case. 

Let  us  now  consider  the  comparative  weights  of  dried,  shelled  peas 
produced  by  the  different  salt  applications  (see  fig.  20).    The  results 


500 


400 


g  300 


y 


y 


■i 


c*_ i x 


s 


I 


\ 


l 


\ 


L 


\ 


100 


r 


..±13.. 


.K. 


PQ* 


Dates  sampled. 

Fig.  12. — Water-soluble  materials  dissolved  from  cropped  pot  soils  receiving 
both  superphosphate  and  calcium  carbonate. 


are  slightly  different  from  those  considered  above.  The  calcium  car- 
bonate and  the  superphosphate  treatments  alone  produced  significant 
increases,  while  treatments  of  sodium  nitrate  and  of  potassium  sulfate 
apparently  decreased  the  yields,  although  the  decreases  are  hardly 
significant.  One  can  see  from  the  data  presented  that  liming  to 
neutrality  is  the  treatment  par  excellence  for  this  soil  type  where 


374 


University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 


optimum  moisture  and  temperature  conditions  obtain.  The  use  of 
superphosphate  without  lime  increases  the  yield  of  peas  but  6%, 
while  the  addition  of  lime  alone  gives  us  an  18%  increase  over  the 
check  pots.  In  treatment  8,  where  both  lime  and  superphosphate 
are  applied,  the  yield  is  the  same  as  where  lime  alone  is  used.  The 
soil  solubility  studies  to  follow  explain  this  point  by  showing  that 
the  calcium  carbonate  application  renders  soluble  such  amounts  of  soil 


Dates  sampled. 

Fig.    13. — Effects    of    different    treatments    on    specific    resistances    of    water 
extracts. 


phosphorus  that  still  further  applications  of  this  element  are  unneces- 
sary (see  fig.  18,  curves  4  and  8).  At  no  time  during  the  develop- 
ment of  the  plants  in  the  greenhouse  was  the  presence  of  soil  toxins 
in  any  way  manifested.  Certain  other  points  of  interest  regarding 
comparative  yields  will  be  noted  later  in  connection  with  the  soil 
solubility  studies. 

Immediately  after  harvesting  (on  April  10),  the  soils  were  care- 
fully removed  from  the  pots  and  the  roots  examined  for  nodule  pro- 
duction. Previous  experience  in  the  field  had  shown  this  soil  to  be 
well  supplied  with  the  strain  of  B.  radicicola  capable  of  producing 


1922]  Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas  375 

nodules  on  pea  roots.  There  was  but  little  variation  between  the 
individual  pots  of  the  same  treatment,  the  following  general  statements 
applying  in  each  ease : 

Treatment  No.  1 :  A  few  large  nodules.    Several  small  ones  per  pot. 
Treatment  No.  2:  Similar  to  No.  1.     Possibly  a  few  more  small 

nodules. 
Treatment  No.  3 :  A  very  few  small  nodules.    But  slightly  better 

than  No.  5. 
Treatment  No.  4 :  Best    of    all    treatments.      Large    numbers    of 

nodules  both  large  and  small.    Many  near  bottom  of  pots. 
Treatment  No.  5  :  No  nodules  found. 
Treatment  No.  6 :  Very  large  numbers  of  small  nodules.    No  large 

clusters. 
Treatment  No.  7 :  Large   numbers  of  nodules,   chiefly  small,   al- 
though a  few  large  clusters  were  noted.    Almost  as  good  as  No.  4. 
Treatment  No.  8 :  Very  few  small  nodules.    Similar  to  No.  3. 
At  first  thought  it  might  seem  incredible  that  such  an  acid  soil 
(PH  4.5)  could  harbor  viable  strains  of  B.  radicicola.  Fred  and  Daven- 
port,12 however,  in  a  series  of  very  carefully  controlled  experiments, 
have  given  data  to  show  that  certain  of  the  B.  radicicola  group  are 
very  resistant  to  acidity.    All  of  the  species  apparently  may  withstand 
a  reaction,  in  liquid  media,  of  PH  5.    They  state : 

The  nodule  bacteria  from  different  plants  behave  very  differently  toward  acid. 
The  legume  bacteria  may  be  divided  into  groups  about  as  follows: 

1.  Critical  Ph — 4.9     Alfalfa  and  sweet  clover. 

2.  Critical  Ph — 4.7     Peas  and  vetch. 

3.  Critical  Ph — 4.2     Clover  and  common  beans. 

4.  Critical  Ph — 3.3     Soy  and  velvet  beans. 

5.  Critical  Ph — 3.15  Lupines. 

The  evidence  supports  the  conclusions  that  a  correlation  exists  between  the  acid 
resistance  of  the  bacteria  and  the  acid  resistance  of  the  higher  plant. 

Since  their  bacteriological  work  was  carried  on  in  solution  cultures, 
it  may  not  be  directly  comparable  with  soil  conditions,  although  it 
should  be  added  that  beans  on  the  soil  under  experiment  grow  better 
than  do  either  peas  or  alfalfa.  This  sequence  would  be  expected  from 
the  data  above  presented. 

Upon  further  observance  of  the  effect  of  the  -soil  treatments  on 
nodule  formation,  we  note  that  where  nitrates  were  added,  no  nodules 
appeared,  and,  contrary  to  expectation,  where  CaC03  was  applied  to 
neutrality  but  very  few  small  nodules  were  found.  The  reason  is 
probably  the  same  in  both  cases    (see  fig.  19,  curves  3,  5,   and  8), 


376 


University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 


namely,  a  superabundance  of  nitrate-nitrogen.  Many  articles  are  ex- 
tant showing  the  depressing  tendency  of  large  amounts  of  soil  nitrates 
on  nodule  formation.  Superphosphate  has  often  been  observed  to 
enhance  nodule  production.  Our  studies  are  in  agreement  with  these 
findings.  Potash  and  gypsum  treatments  but  slightly  enhanced 
nodule  formation. 


5     6 


H 


Dates  sampled. 

Fig.  14. — Effects  of  different  treatments  on  hydrogen-ion  concentrations  of 
soils. 


Sail  Extraction  Studies 

It  remains  for  us  to  discuss  the  interesting  data  secured  by  periodi- 
cally extracting  the  differently  treated  soils  with  distilled  water  and 
noting  the  effects  of  both  the  fertilizer  applications  and  the  growing 
plants  upon  the  concentration  of  soil  solutes.  The  importance  of 
knowledge  of  both  the  direct  and  the  indirect  effects  of  fertilizer  chem- 
icals upon  soils  has  been  briefly  pointed  out  in  the  introduction  to 
these  studies.  Stewart44  has  shown  very  fully  the  effects  of  a  growing, 
unfertilized  crop  of  barley  upon  the  concentration  of  the  soil  solution. 
During  the  first  six  to  eight  weeks,  a  considerable  increase  in  soluble 
nutrients  was  usually  observed.  This  was  especially  true  of  nitrates. 
The  growing  crop  then  began  to  draw  heavily  upon  this  store  with  the 


1922] 


Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas 


377 


result  that  in  most  soils  a  gradual  decrease  in  concentration  was  noted. 
He  found  that  fertile  soils  were  sometimes  exceptions  to  this  rule,  the 
concentrations  remaining  practically  constant  throughout  the  entire 
growth  period.  The  cause  of  this  was  pointed  out  as  being  doubtless 
due  to  the  abilities  of  very  fertile  soils  to  renew  soluble  materials  as 


Dates  sampled. 
Fig.  15. — Effects  of  different  treatments  on  calcium-ion  solubility. 

rapidly  as  they  were  withdrawn.  Hoagland,21  Millar,34  and  McCool 
and  Millar32  have  shown  that  the  solutes  in  the  soil  solution  vary 
greatly  at  different  periods  and  are  materially  affected  by  the  growth 
of  plants. 

In  the  present  investigation  such  effects  are  well  shown  in  the 
curves  presented  in  fig.  5.  Upon  the  abscissae  have  been  plotted  the 
dates  of  sampling,  while  upon  the  ordinates  appear  the  concentrations 


378 


University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 


of  the  various  ions  in  parts  per  million  of  dry  soil.  Table  VIII  lists 
the  data  from  which  these  curves  were  constructed.  The  graphs 
represent  results  secured  from  the  eight  check  pots  which  received  no 
fertilizing  materials.  Only  slight  differences  in  water-soluble  potas- 
sium, magnesium,  calcium,  and  phosphorus  are  here  shown  at  the 
different  sampling  dates,  while  during  the  last  two  months  a  gradually 
declining  tendency  is  noticed.    The  absolute  amounts  of  these  elements, 


150 


•-    100 


Dates  sampled. 
Fig.  16. — Effects  of  different  treatments  on  magnesium-ion  solubility. 

present  in  a  readily  soluble  form,  are  above  those  usually  secured  from 
the  poor  soils  reported  by  Stewart,  with  the  exception  of  P04-ion, 
the  amount  of  which  is  unusually  low.  The  nitrate-ion  gradually 
increased  in  quantity  during  the  first  two  months  of  growth,  then  fell 
off  until,  at  the  time  of  crop  maturity,  none  remained.  The  results 
of  the  chemical  work  as  carried  out  on  the  untreated  field  plot  soils 
(fig.  3)  are  in  close  agreement  with  the  greenhouse  checks,  except  that 
nitrates,  in  the  field,  at  no  time  equal  the  large  quantities  at  first 
present  in  the  irrigated  pot  soils. 

Let  us  now  briefly  consider  the  effects  of  the  several  treatments 
upon  the  solubilities  of  the  constituents  of  this  clay  loam  soil.     The 


1922] 


Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas 


379 


cheek  pots,  which  received  no  additions,  will  be  taken  as  the  basis  for 
comparison.  Both  the  cropped  and  fallowed  soils  will  be  discussed. 
The  specific  resistances  of  the  soil  extracts  were  always  determined 
and  are  of  importance  in  that  they  give  us,  in  such  dilute  solutions,  a 
comparative  measure  of  total  soluble  salt  concentrations.  One-tenth 
of  the  specific  resistance,  in  ohms,  is  shown  by  the  solid  lines  in  the 
graphs.    It  will  be  seen  that  these  vary  inversely  with  the  concentra- 


Dates  sampled. 
Fig.  17. — Effects  of  different  treatments  on  potassium-ion   solubility. 

tion  of  soil  solutes  and  that  a  general  relationship  exists  between  water- 
soluble  salts  and  crop  production. 

Gypsum  at  the  rate  of  one  ton  per  acre  was  applied  to  the  pots  in 
treatment  2  (see  fig.  6).  Contrary  to  many  general  statements  in  the 
literature,  nitrate  production  has  not  here  been  appreciably  affected. 
The  amount  of  water-soluble  magnesium,  however,  has  been  increased 
almost  threefold,  while  the  amount  of  soluble  potassium  has  been 
doubled  under  a  rapidly  growing  crop.  The  amount  of  phosphate-ion 
was  slightly  increased  at  first,  but  soon  fell  to  the  level  of  the  checks. 
Calcium,  as  would  be  expected,  remained  at  a  high  level  throughout 
the  experiment.     Sulfates,  occasionally  determined  but  not  shown  in 


380 


University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 


the  graphs,  were  highest  in  the  gypsum  treatments.  In  the  fallowed 
soils  (Table  IX),  the  results  were  much  the  same,  except  that  the  high 
level  of  concentration  occurred  a  little  later  for  all  of  the  ions  except 
magnesium.  Here  there  was  a  gradual  progressive  increase.  The 
actual  concentrations  of  water-soluble  compounds  in  the  fallowed  soils 
in  all  cases  reached  much  higher  levels  than  were  reached  in  the 
cropped  pots. 


3    5 


&    4 


Dates  sampled. 
Fig.  18. — Effects  of  different  treatments  on  phosphate-ion  solubility. 

The  CaC03  applications  increased  nitrate  production  (from  soil 
nitrogen)  at  least  threefold  throughout  the  growing  period  (see  fig.  7). 
The  same  is  true  of  the  production  of  soluble  magnesium.  Soluble 
potassium  and  phosphorus  are  each  increased  by  approximately  50 
per  cent.  Calcium,  in  a  readily  water-soluble  form,  has  been  increased 
from  an  average  of  40  p.  p.  m.  in  the  checks  to  over  300  p.  p.  m.  in  the 
lime-treated  pots.  The  specific  resistance  of  the  soil  extract  is  very  low 
throughout.  With  the  exception  of  nitrate  (and  this  tendency  is  also 
shown  in  the  uncropped  soil)  the  lime  treatment  not  only  maintains 
the  concentrations  of  the  several  ions  during  the  period  of  vigorous 
absorption  of  solutes,  but  actually  increases  the  rate  of  solubility  of 


1922] 


Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas 


381 


minerals  over  and  above  crop  demands,  for  we  see  that,  on  March  20, 
at  the  time  of  maturity  there  is  shown  a  slight  rise  in  the  phosphorus, 
potassium,  magnesium,  and  calcium  curves  over  the  previous  sampling 
date.  It  will  be  recalled  that  the  CaC03  treated  pots  produced  the 
maximum  crops.  In  the  fallowed  soil  (Table  IX),  the  carbonate 
treatment  produced  by  far  the  largest  amount  of  soluble  material,  as 
shown  by  the  specific  resistances.    In  this  case,  also,  the  greatest  con- 


Dates  sampled. 
Fig.  19. — Effects  of  different  treatments  on  nitrate-ion  solubility. 

centration  of  solutes  appeared  some  weeks  later  than  in  the  cropped 
soil.  Magnesium  was  an  exception.  Here  progressive  solubility  was 
gradual  throughout.  In  both  cropped  and  fallowed  soils,  gypsum 
and  calcium  carbonate  were  about  equally  effective  in  increasing  mag- 
nesium solubility.  A  simple  interchange  of  bases  may  possibly  account 
for  this.  The  solubility  of  the  soil  potassium  is  affected  but  slightly 
by  the  CaC03  additions. 

Figure  8  shows  the  effect  of  superphosphate  treatment.  Figure  4, 
which  records  similar  data  for  the  field  plots,  may  also  here  be  of  com- 
parative interest.  A  notable  similarity  is  shown  between  the  two.  A 
comparison  of  figure  8  with  the  check  pots,  figure  5,  shows  the  addition 


382  University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 

of  superphosphate  to  have  practically  doubled  the  amounts  of  water- 
soluble  phosphorus,  calcium,  and  magnesium  throughout  the  duration 
of  the  experiment,  while  nitrate  formation,  contrary  to  expectation, 
was  slightly  depressed  by  it.  The  same  holds  true,  in  the  case  of 
nitrates,  for  the  fallowed  soils,  although  nitrification  in  both  cases 
increased  at  first  more  rapidly  in  the  presence  of  the  soluble  phos- 
phorus. In  this  series  the  cropped  and  uncropped  soils  behaved  very 
similarly  as  regards  progressive  solubility ;  the  soil,  when  receiving  an 
application  of  acid  phosphate,  apparently  being  able  to  maintain  the 
important  solutes  at  fairly  high  concentrations  during  crop  with- 
drawals. 

The  results  for  the  NaN03  treatment  are  shown  in  figure  9.  With 
the  exception  of  the  large  amount  of  added  nitrate,  there  is  little 
difference  between  these  soils  and  the  checks.  Thus,  the  nitrate  appli- 
cation has  had  very  little  effect  in  increasing  the  solubility  of  this 
soil's  constituents.  This  is  in  accordance  with  the  recent  work  of 
Bauer,3  who  found  that  the  presence  of  NaN03  had  no  effect  upon  the 
availability  of  soil  phosphorus,  and  of  Jensen,23  who  concluded  that 
nitrate  applications  had  no  effect  upon  potassium  availability  and 
actually  decreased  a  soils  soluble  phosphate  content.  Spurway,43  on 
the  other  hand,  shows  additions  of  NaN03  to  considerably  increase 
the  solubility  of  phosphorus  and  magnesium  in  the  sandy  soils  which 
he  investigated.  The  increases,  however,  are  irregular,  and  the  con- 
ditions imposed  are  most  artificial.  The  fallowed  soils  receiving  NaN03 
gave  increases  over  the  checks,  although  the  increments  were  small  in 
comparison  with  those  noted  for  other  treatments.  The  crop  results 
further  showed  that  nitrate  applications  were  unwarranted.  The 
specific  resistances  were  here  at  first  slightly  lower  than  were  those 
of  the  checks,  due  to  the  soluble  nitrate  application,  but  even  this 
difference  disappeared  as  the  end  of  the  growing  period  was  reached. 

The  potassium  sulfate  application,  although  slightly  increasing 
water-extractable  soil  materials,  also  had  no  enhancing  effect  upon 
yields.  It  was  applied  at  the  rate  of  500  pounds  per  acre.  Figure  10 
shows  that  water-soluble  lime  and  potash  have  each  been  slightly 
increased  during  the  period  of  active  growth.  The  solubility  of  the 
phosphorus  has  been  unaffected,  as  has  nitrate  production.  Mag- 
nesium has  been  increased.  The  results  secured  with  potassium 
sulfate  in  the  fallowed  soil  are  in  fair  agreement  with  these.  The 
general  relationships  hold,  although  slightly  larger  quantities  of  solutes 
appear  in  all  cases.    A  slow  progressive  solubility  is  recorded  for  each 


1922]  Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas  383 

ion  determined  except  calcium,  which  apparently  assumes  its  maximum 
concentration  about  a  month  or  six  weeks  after  the  addition  of  the 
potassium  sulfate  and  thereafter  gradually  declines.  None  of  the 
solubility  increases  is  marked. 

In  treatment  7,  superphosphate  (one  ton  per  acre),  together  with 
potassium  sulfate  (500  pounds  per  acre),  was  added.  The  effects 
upon  the  solubility  of  the  various  ions  determined  are  shown  in  figure 
11.  As  would  be  expected,  the  soluble  salt  content  has  been  consider- 
ably increased.  Nitrates,  however,  remain  approximately  as  in  the 
check  pots.  No  uncropped  soils  carrying  two-salt  treatments  were 
maintained.  The  yields  here  were  a  surprise — much  below  those 
where  superphosphate  alone  had  been  used.  This  may  be  due  to 
"alkali,"  for  analysis  showed  that  Na.,S04  was  present  slightly  in 
excess  of  0.2  per  cent.  Improper  balance  of  salts  may  also  be  advanced 
as  a  possible  explanation  for  the  lowered  yields,  as  sulfate,  calcium, 
magnesium,  and  potassium-ions  are  present  in  large  quantities,  while 
nitrates  are  present  in  relatively  low  amounts. 

In  the  last  series,  applications  of  superphosphate  and  CaC03  were 
the  treatments  employed.  The  concentrations  of  the  soil  extracts  were 
decidedly  increased  (see  fig.  12),  as  shown  by  the  conductivity  meas- 
urements. The  Ca-,  N03-,  and  P04-ions  especially  showed  greatly 
increased  solubility.  No  tendency  toward  a  decline  in  concentration 
during  the  period  of  rapid  growth  was  evident.  That  soluble  phos- 
phate applications  are  superfluous  when  this  soil  is  neutralized  with 
lime  is  shown  in  figure  7.  The  ability  of  CaC03  to  set  free  soluble 
phosphorus  from  soil  minerals  has  also  been  recorded  by  Praps,11 
Hartwell  and  Kellogg,18  Guthrie  and  Cohen,14  and  others. 

In  order  to  compare  more  easily  the  effects  of  the  individual  treat- 
ments upon  the  solubility  of  each  ion,  a  second  series  of  curves  was 
prepared.  The  complete  hydrogen-ion  and  conductivity  data  are  also 
presented.  Let  us  glance  at  figure  13,  which  shows  the  effects  of  each 
treatment  (1  to  8)  upon  the  periodically  determined  specific  resist- 
ances. The  determination  of  specific  resistance  upon  soil  extracts  is 
at  the  present  time  meeting  with  considerable  favor  among  soil  investi- 
gators. In  alkali  studies,  where  large  numbers  of  soils  must  be  ex- 
amined for  total  soluble  salts,  its  use  is  certainly  to  be  recommended. 
That  considerable  precision  may  be  claimed  for  it  has  been  shown  by 
von  Horoath,22  who  has  proposed  a  soil  classification  based  upon  elec- 
trical conductivity.  In  figure  13,  the  high  concentrations  of  treatments 
8  and  3  (where  CaC03  was  added)  over  the  entire  growth  period  are 


384  University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 

well  shown,  while  the  low  concentrations  of  the  checks  (1),  the  K2S04 
pots  (6),  and  the  nitrate  treated  soils  (5),  are  likewise  emphasized. 
Numbers,  2,  4,  and  7  occupy  intermediate  positions.  That  the  yields 
may  be  closely  correlated  with  soluble  salt  concentrations  (conduc- 
tivities) has  been  previously  noted.  A  comparison  with  figure  20 
emphasizes  this  fact. 

Considerable  interest  attends  the  data  presented  in  figure  14. 
Hydrogen-ion  determinations  were  made  periodically  upon  these 
pot  soils  throughout  the  experiment,  much  care  being  taken  to  secure 
accurate,  comparative  results.  It  was  desired  to  ascertain  whether  or 
not,  during  the  growth  of  the  crop,  any  of  the  fertilizer  treatments, 
except,  of  course,  CaC03,  had  in  any  way  altered  soil  reaction,  and 
also  whether  or  not,  after  adding  CaC03  to  neutrality,  any  acidity 
subsequently  developed.  The  abscissa  shows  the  dates  of  sampling, 
while  the  ordinate  is  divided  into  the  customary  PH  units.  The  small, 
ten-gram  samples  used  in  making  these  determinations  were  carefully 
taken  from  the  large  monthly  composite  samples  and  were  repre- 
sentative. The  determinations  were  made  upon  the  moist  soils  as 
soon  as  received  from  the  greenhouse.  A  study  of  figure  14  shows 
that  in  treatments  3  and  8,  sufficient  CaC03  had  been  added  to  main- 
tain an  alkaline  reaction  (above  PH7),  although  the  tendency  to 
gradually  decrease  in  alkalinity  is  shown  at  the  last  two  sampling  dates. 
While  exactly  the  same  amounts  of  CaC03  were  supplied  in  both  cases, 
it  will  be  seen  that  the  addition  of  superphosphate  in  treatment  8 
rendered  this  soil  more  alkaline  at  all  times.  The  same  tendency  to 
induce  alkalinity  is  shown  where  superphosphate  is  added  alone 
(compare  treatment  3  with  treatment  1),  the  checks  being  the  most 
acid  soils  of  all.  These  results  are  in  direct  agreement  with  those  of 
Conner,*  who  has  shown  that  soils  that  had  been  treated  with  acid 
phosphate  for  twenty  years  were  less  acid  than  the  untreated  soils. 
Morse38  has  determined  hydrogen-ion  concentrations  colorimetrically 
on  certain  plot  soils.  In  agreement  with  other  investigators,  he  claims 
that  acid  phosphate,  even  though  used  over  a  long  period  of  years, 
produced  no  noticeable  effect  on  soil  reaction,  while,  where  lime  was 
occasionally  used  with  it,  at  the  rate  of  one  ton  per  acre,  the  super- 
phosphate apparently  further  enhanced  alkalinity.  Small,  definite 
differences  also  existed  between  the  checks  and  the  soils  receiving  the 
neutral  salt  treatments.  It  will  be  seen  that  the  K2S04  application 
has  decreased  the  hydrogen-ion  concentration  throughout  by  at  least 
three-tenths  of  a  PH — an  amount  too  great  to  be  considered  experi- 


1922]  Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas  385 

mental  error.  This  basic  tendency  of  the  other  salts,  while  less  pro- 
nounced, is,  however,  uniform  and  definite. 

A  decided  upward  trend  of  all  of  the  curves  (except  3  and  8)  is 
noticeable  from  February  20  to  March  20.  The  decreases  in  hydrogen- 
ion  concentration  are  here  too  marked  to  be  ascribed  to  error.  A  pos- 
sible explanation  for  this  is  as  follows:  At  the  end  of  the  growing 
season,  a  small  fraction  only  of  the  nitrate  still  remains  in  these  very 
acid  soils  (see  figure  19).  The  soil  solution  must  be  practically 
saturated  with  C02  due  to  rapid  root  growth  and  high  organic  matter 
content.  When  the  large  amounts  of  nitrate  are  absorbed  and  removed 
from  solution,  the  bases  formerly  associated  with  this  strongly  acid 
radical  may  combine  with  the  weak  H,CO;i  forming  bicarbonates  of 
the  strong  bases  (K,  Na,  Ca).  Subsequent  hydrolysis  tends  slightly  to 
increase  OH-ion  concentration. 

Another  point  which  the  writer  deems  of  importance  in  connection 
with  the  reaction  studies  recorded  is  that  strong  soil  acidity,  per  se, 
is  not  necessarily  harmful  to  growth,  and  that  it  has  in  the  past  been 
over-emphasized  as  a  cause  of  low  productivity,  especially  in  the  case 
of  leguminous  crops.  A  glance  at  figure  21,  together  with  the  high 
yields  secured  in  all  cases,  checks  included,  suffices  to  show  that,  even 
where  such  a  "lime  loving"  legume  as  the  pea  is  grown,  other  con- 
ditions being  optimum,  good  results  may  be  expected  in  the  presence 
of  high  soil  acidity.  So  far  as  the  writer  is  aware  there  is  no  definite 
evidence  in  the  literature  to  show  that  soil  acidity  of  itself  is  the 
direct  cause  of  infertility.  Recent  work  at  the  University  of  Cali- 
fornia might  be  cited  to  show  that  heavy  yields  are  often  secured  in 
solution  cultures  where  hydrogen-ion  concentrations  are  abnormally 
high.  It  is  thus  questionable  whether  complete  neutralization,  espe- 
cially where  high  lime  applications  are  necessary,  is  ever  justified. 
Many  cases  have  been  noted  where  the  satisfaction  of  a  small  fraction 
of  the  so-called  "lime  requirement"  has  increased  yields  to  the  same 
extent  as  have  larger  lime  treatments. 

The  comparative  calcium-ion  concentrations  in  the  variously  treated 
soils  appear  in  figure  15.  In  treatment  8,  receiving  both  CaC03  and 
superphosphate,  we  find  the  most  soluble  calcium.  This  is  followed 
by  CaC03,  gypsum,  superphosphate  plus  K2S04,  and  superphosphate 
alone.  The  K2S04  and  the  NaN03  treatments  had  little  effect  in 
setting  free  soil  calcium. 

The  behavior  of  magnesium-ion  is  of  interest  in  that  it  follows 
closely  that  of  calcium-ion  solubility.    A  comparison  of  figure  16  with 


386  University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 

figure  15  shows  that  there  are  no  exceptions  to  this  statement.  As 
magnesium  was  in  no  case  applied  to  the  soils*  in  soluble  form,  there 
must  have  been  a  direct  exchange  of  bases  between  this  ion  and  those 
supplied  in  the  treatments. 

The  solubility  of  soil  potassium  has  been  fully  discussed.  A 
direct  graphical  comparison  of  the  treatments  is  shown  in  figure  17. 
The  check  soils  (number  1)  are  the  lowest  in  available  potassium 
throughout,  while,  aside  from  the  direct  K2S04  treatments,  gypsum  is, 
in  the  soil  under  study,  apparently  superior  to  all  others  in  setting 
free  potash.  The  efficacy  of  the  superphosphate  additions  is  here 
doubtless  due  to  this  ingredient.  Recent  work  of  McCool  and  Millar33 
bears  out  this  statement.  Calcium  carbonate  is  much  less  effective. 
Slight  increases  only  result  from  the  NaN03  applications. 

The  percentage  of  water-soluble  phosphate  is  unusually  low  in 
this  soil  and  none  of  the  treatments,  except  those  directly  supplying 
phosphate-ion,  greatly  alters  its  availability  save  CaC03  which  has  a 
slightly  enhancing  tendency  toward  the  end  of  the  experimental  period. 
The  check  soils  are  a  little  below  the  others  in  the  amounts  of  soluble 
phosphorus  they  contain,  as  shown  in  figure  18,  although  the  differ- 
ences are  slight.  That  low  concentrations  of  P04-ion  are  the  rule  in 
water  extracts  of  soils  has  often  been  recorded.  Certain  data  recently 
secured  by  the  writer  have  shown  that  the  same  holds  for  the  true 
soil  solution  as  obtained  by  a  direct  pressure  method.  One  to  three 
p.  p.  m.  of  soil  solution  are  here  usually  found.  "Work  in  this  con- 
nection has  been  reported  elsewhere,  f 

The  nitrate-ion  concentrations  as  plotted  in  figure  19  are  of  interest 
in  that  they  closely  agree  with  nitrification  studies  (not  here  reported). 
Except  number  5,  where  NaNO:i  was  directly  supplied,  the  CaC03 
treatments  alone  gave  noteworthy  increases.  In  all  cases,  however, 
sufficient  nitrification  may  have  taken  place  within  this  acid  soil  to 
supply  crop  requirements,  although  it  should  be  recalled  that  a  legu- 
minous crop  was  grown. 

While  the  results  of  these  solubility  studies  apply  to  this  soil  alone, 
we  are  probably  safe  in  considering  them  generally  applicable  to 
transported,  low-lying  acid  clays  and  clay  loams,  comparatively  high 
in  organic  matter  and  rich  in  nitrogen. 


*  The  superphosphate  alone  gave  slight  traces. 
t  See  Soil  Science,  vol.  13. 


1922]  Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas  387 


SUMMARY 

The  work  herein  reported  embraces  an  investigation  of  an  acid, 
marsh  soil,  unproductive  for  peas,  by  the  use  of  certain  of  the  more 
modern  procedures.  Both  field  and  greenhouse  experiments  were  con- 
ducted, a  variety  of  fertilizing  materials  were  employed,  and  soil- 
water-extracts,  periodically  made,  were  studied  to  ascertain  the  rates 
of  formation,  as  well  as  the  absolute  amounts,  of  soluble  salts  formed 
in  the  soil  when  influenced  by  the  different  factors  involved.  This 
work  has  been  supplemented  by  hydrogen-ion  determinations  and  con- 
ductivity measurements.  A  detailed  discussion  of  the  results  secured 
has  been  given  in  the  body  of  the  text,  although  a  critical  study  of 
the  data  presented  offers  several  points  of  theoretical  interest. 

Doubtless,  the  most  important  point  made,  aside  possibly  from  the 
effects  of  the  various  treatments  upon  yields,  is  the  remarkable  indirect 
fertilizing  action  of  certain  of  the  chemical  compounds  when  applied 
to  this  cropped,  clay-loam  soil.  That  this  has  been  brought  about  by 
a  process  of  ionic  substitution,  element  for  element,  within  the 
hydrated  silicate  molecules,  thereby  greatly  increasing  mineral  solu- 
bility, is  a  probable  explanation.  Why  certain  bases,  as  calcium  for 
instance,  should  be  more  active  than  sodium  or  potassium  or  why  the 
S04-ion  should  be  more  reactive  than  either  N03-ion  or  P04-ion  are 
questions  offering  a  good  field  for  hypothesis  and  experiment. 

In  comparing  field  and  greenhouse  yields  we  see  that  while  CaC03 
had  no  effect  whatever  in  the  field,  in  the  pot  experiment  it  gave  the 
largest  crop.  With  superphosphate  the  results  were  reversed.  As 
this  was  an  unusually  dry  year  in  the  field,  while  in  the  greenhouse 
moisture  conditions  were  maintained  at  optimum,  an  explanation  may 
possibly  lie  in  the  comparative  solubilities  of  these  two  compounds. 
The  action  of  the  CaC03,  being  in  large  part  due  to  its  indirect  effect 
through  enhanced  nitrification,  requires  considerable  quantities  of 
water,  while,  on  the  other  hand,  if  sufficient  moisture  is  present  to 
dissolve  but  a  small  portion  of  the  superphosphate,  enhanced  yields 
should  result  in  a  soil  deficient  in  available  phosphorus.  Another 
effect  of  the  field  application  of  acid  phosphate  was  to  increase  per- 
manently the  solubilities  of  all  of  the  soil  constituents  except  P04-ion. 
Soluble  phosphorus  was  directly  supplied,  yet  at  the  end  of  two 
months  no  indications  of  such  applications  were  apparent  in  the  water 


388 


University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 


extracts.  Similar  conditions  were  observed  in  the  greenhouse  pot 
soils.  It  has  been  noted  that  small  quantities  (12  to  14  p.  p.  m.)  of 
soluble  aluminum  were  consistently  found  in  this  soil.  A  simple 
explanation  of  rapid  phosphate  reversion  may  thus  be  found  in  a 
direct  union  between  superphosphate  and  soluble  aluminum,  with 
the  formation  of  insoluble  aluminum  phosphate.  In  a  soil  rendered 
alkaline  with  lime,  however,  no  such  reaction  could  occur  due  to  the 
precipitation  of  all  soluble  aluminum,  either  as  the  hydroxide  or  as 


0 

K 

i/tJ 

±5.6 

« 

HO 

±3.^ 

±2.1 

±21 

±2.1 

tu 

5* 

^0 

in 

c5 

*/s 

±23 

K> 

*> 
4! 
U 

k| 

4 
0 

T 

I 

3 
0 
0. 

V 

OTA 

i 

\ 

KY 

5! 

"1 

+ 

I 

0 

£i.L 

£D 

±12 

±01 

S/i 

0 

01 

il.S 

±u 

/    Z     3    4-    5    6     7    S  /    Z    3    4-    5    6    7    a 

TFtCATMEHTS  _ 

Fig.  20. — Comparative  yields  per  pot  of  total  dry  matter  and  cured  peas. 


calcium  aluminate,36  as  well  as  to  the  early  formation  of  the  reverted 
calcium  phosphate  which,  so  far  as  crops  are  concerned,  is  largely 
available.  Such  conditions  do  obtain  in  the  CaC03-treated  pots  where 
maximum  yields  were  registered  and  where  moisture  conditions  were 
optimum.  The  curves  here  also  show  a  slightly  enhanced  phosphate 
solubility  which  is  maintained  throughout  the  growing  period. 

A  careful  study  of  figures  5,  7,  11,  and  12,  together  with  compara- 
tive yields  for  these  treatments  (figure  20),  casts  some  doubt  as  regards 
the  power  of  soluble  phosphorus  to  increase  yields  greatly  in  this 
soil  unless  soluble  calcium  also  is  present  in  adequate  amounts.  In 
figure  11  (superphosphate  -+-  K,S04)  fairly  large  quantities  of 
soluble  P04-ion  obtain   (in  fact,  larger  than  appear  in  the  CaC03- 


1922] 


Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas 


389 


treated  pots),  yet  the  yields  are  greatly  in  favor  of  the  CaC03  addi- 
tions. Large  percentages  of  soluble  calcium  are  shown  at  all  times  in 
figure  7.  In  figure  11,  however,  less  than  one-half  of  these  amounts 
is  present,  while  magnesium-ion  concentration  in  this  case  is  almost 
equal  to  that  of  calcium-ion.  These  results  may  show  that  a  certain 
balance  of  ions  within  soil  solutions  is  essential  for  optimum  plant 
growth. 


■ 


i 


Fig.  21. — Plants  one  month  before  harvesting,  showing  the  eight  treatments. 


Similar  indications  of  the  necessity  for  proper  ionic  ratios  are 
shown  in  figures  7  and  9  where  nitrates,  phosphates,  potassium,  and 
calcium  may  be  compared.  The  proportion  of  nitrates  is  high  in 
both  cases ;  the  amounts  of  phosphates  differ  but  1  to  2  p.  p.  m.,  as  is 
also  the  case  with  potassium,  but  calcium-ion  is  increased  sixfold  in 
the  CaC03  treatment  where  the  maximum  yields  are  recorded.  Other 
examples  might  be  given  which  indicate  that  where  anions  are  high, 
cations  must  also  be  present  in  certain  definite  optimum  proportions. 

A  glance  at  the  periodical  conductivity  measurements  on  the 
extracts  from  the  variously  treated  soils  shows  that  they  arrange  them- 
selves exactly  in  the  order  of  productivity.  This  method  has  been 
shown  to  be  of  great  value  in  the  study  of  alkali  soils  where  large 
quantities  of  soluble  salts  prevail.  May  it  not  be  of  still  greater  value, 
in  the  absence  of  alkali,  where  estimates  of  comparative  fertility  are 
desired  ? 


390  University  of  California  Publications  in  Agricultural  Sciences       [Vol.4 

Soil  acidity  has  been  fully  discussed  in  the  light  of  data  here  pre- 
sented and,  except  in  the  presence  of  unusually  high  hydrogen-ion 
concentrations  (below  PH4.5),  it  seems  doubtful  to  the  writer  that 
acidity,  per  se,  is  ever  the  direct  cause  of  low  productivity  provided 
sufficient  concentrations  of  the  basic  ions  (Ca,  Mg,  K)  are  present 
within  the  soil  solution. 


CONCLUSIONS 

The  following  general  conclusions  may  be  drawn  as  the  result  of 
these  investigations: 

These  studies  were  carried  out  on  an  acid,  drained,  heavy  clay- 
loam,  marsh  soil  of  the  San  Francisco  Bay  region  which  was  unpro- 
ductive for  certain  crops  and  carried  small  percentages  of  the  white 
alkali  salts,  notably  sulfates. 

Nitrification  studies  showed  that  the  addition  of  calcium  carbonate 
to  neutrality  greatly  increased  nitrate  production,  while  soluble  phos- 
phorus and  potassium  compounds,  without  lime,  produced  no  effect. 
Ammonification  was  largely  due  to  soil  fungi,  and  the  Azotobacter 
species  were  absent. 

A  statistical  study  of  the  factor  of  variability,  where  certain  water- 
soluble  ions  within  soil  extracts  were  taken  as  the  criteria,  showed  that 
apparently  uniform  field  soils  may  vary  greatly  within  small  areas; 
this  is  in  accordance  with  the  recent  work  of  Waynick  and  Sharp.48 

In  the  field,  water  was  apparently  the  limiting  factor  in  crop  pro- 
duction at  the  Marin  Meadows  Ranch  during  the  1919-1920  season. 
Under  those  conditions  superphosphate  applied  at  the  rate  of  one  ton 
per  acre  increased  yields  by  approximately  25  per  cent  while  liming 
to  neutrality  gave  no  increases  over  the  check  plots.  The  chemical 
control  maintained  throughout  the  duration  of  the  field  experiment 
showed  that  the  acid-phosphate  applications  had  greatly  enhanced  the 
solubility  of  soil  K,  Mg,  and  Ca,  while  nitrate  production  was  affected 
but  slightly.  The  rapid  revision  of  soluble  phosphate  within  this  soil 
was  thought  to  be  due  largely  to  the  formation  of  aluminum  phosphate, 
for  a  small  amount  of  aluminum-ion  was  always  present  in  water 
extracts  of  this  soil.  Ferrous  compounds  or  other  toxic  materials 
aside  from  the  white  alkali  salts  were  not  found. 

In  the  greenhouse,  where  moisture  and  temperature  conditions 
were  optimum,  much  larger  plants  were  produced.     A  35%  increase 


1922]  Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas  391 

(over  the  checks)  in  yield  of  total  dry  matter  attended  the  use  of 
CaC03,  when  added  to  neutrality,  and  a  28%  increase  where  super- 
phosphate at  the  rate  of  one  ton  per  acre  was  applied.  The  soils 
receiving  gypsum  treatments  and  the  checks  were  about  equal  in  pro- 
ductivity, while  NaN03,  and  K2S04,  each  supplied  at  the  rate  of  500 
pounds  per  acre,  gave  slight  but  insignificant  losses.  The  yields  of 
dried  peas  followed  in  a  similar  order. 

Nodule  formation  as  affected  by  these  treatments  within  this  very 
acid  soil  is  discussed.  Nitrates  completely  inhibited  it,  while  CaC03 
added  to  neutrality  acted  similarly  (due  doubtless  to  greatly  enhanced 
nitrification).  The  application  of  soluble  phosphorus  increased  nodule 
formation  while  potassium  sulfate  and  gypsum  produced  no  noticeable 
effects. 

All  of  the  chemical  compounds  added  increased  the  concentration 
of  the  soil  solutions  under  the  growing  crops  when  compared  with  the 
untreated  checks,  although  marked  differences  between  the  several 
treatments  were  noted.  A  direct  relationship  existed  between  the  con- 
centration of  solutes  present  in  the  soil  extracts,  as  shown  by  con- 
ductivity measurements,  and  crop  production.  Gypsum  was  the  most 
active  liberator  of  the  soil  potassium  and  was  equal  to  any  other 
compound  in  effecting  the  solution  of  soil  magnesium,  while  its  action 
upon  phosphorus  availability  and  upon  nitrate  formation  was  nil. 
Calcium  carbonate,  when  added  to  neutrality,  was  apparently  the 
most  effective  soil  solvent  supplied,  although  its  action  was  probably 
largely  indirect.  It  occupies  first  place  in  effecting  the  solution  of 
all  ions,  except  potassium.  In  comparison  with  the  cheeks,  specific 
resistance  was  here  decreased  by  almost  one-half.  This  is  doubtless 
due  to  the  intensive  nitrification  which  this  treatment  engenders. 
Nitrate  production  (from  soil-  N)  was  nearly  trebled,  as  was  water 
soluble  magnesium.  Soluble  calcium  was  increased  many  fold,  and 
soluble  K  and  P04  were  each  increased  by  at  least  one-third.  With 
the  possible  exception  of  nitrate-ion  concentration,  which  likewise  fell 
off  in  the  fallowed  soil,  there  was  no  declining  tendency  noticed  on  the 
part  of  any  of  the  nutritive  ions  during  maximum  withdrawals  by 
the  heavy  pea  crop  produced. 

The  enhanced  solubility  of  soil  minerals  due  to  superphosphate 
applications  is  probably  largely  to  be  attributed  to  the  gypsum  which 
this  material  contains.  Bearing  in  mind  that  approximately  twice  as 
much  calcium  was  supplied  in  the  gypsum  treatments,  the  similarity 
between  the  two  is  strikingly  shown  in  figures  6  and  8.  Soluble 
phoshorus,  of  course,  was  directly  supplied  in  the  superphosphate. 


392  University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 

Sodium  nitrate  had  little  effect  upon  this  soil's  solubility  in  water 
throughout  the  duration  of  the  experiments  here  reported. 

Potassium  sulfate  applications  increased  the  amounts  of  Ca  and 
Mg  going  into  solution  by  possibly  one-third,  while  nitrate  formation 
and  phosphate  availability  were  apparently  unaffected. 

The  results  secured  from  the  two-salt  applications,  both  as  regards 
yields  and  soil  solubilities,  were  approximately  the  same  as  the  average 
of  the  similar  individual  single-salt  treatments. 

A  periodical  study  of  hydrogen-ion  concentration  was  carried  out 
on  each  of  the  differently  treated  pot  soils  throughout  the  cropping 
period.  All  of  the  soils  to  which  neutral  salts  had  been  applied  were 
slightly  but  consistently  less  acid  than  were  the  checks,  superphosphate 
especially  tending  to  lower  H-ion  concentration.  During  heavy  nitrate 
absorption  there  was  a  slow,  definite  increase  in  soil  alkalinity.  On 
the  other  hand,  where  calcium  carbonate  had  been  added  to  neutrality, 
a  progressive  increase  in  H-ion  concentration  was  recorded.  The  ques- 
tion is  discussed  as  to  whether  soil  acidity,  per  se,  is  ever  a  direct  cause 
of  impaired  productivity. 

The  results,  when  cropped  and  fallowed  soils  were  compared, 
differed  but  slightly,  the  chief  dissimilarity  being  that  the  water 
extracts  of  the  fallowed  soils  reached  maximum  concentrations  about 
a  month  later  than  did  those  of  the  cropped  soils,  and  thereafter 
remained  stationary  or  gradually  decreased.  Larger  amounts  of 
solutes  were,  as  a  rule,  present  in  the  uncropped  soils  but  the  same 
comparative  relationships  almost  invariably  held.  A  series  of  fal- 
lowed soils  is  therefore  held  to  be  here  superfluous,  little  additional 
information  being  gained,  while  the  labor  involved  is  approximately 
doubled. 

In  conclusion,  the  writer  wishes  to  express  his  indebtedness  to 
Professor  C.  B.  Lipman,  under  whose  direction  this  work  was  done. 
Thanks  for  many  helpful  suggestions  and  criticisms  are  also  due 
Professor  D.  R.  Hoagland  and  Professor  W.  P.  Kelley. 


1922]  Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas  393 


LITERATURE  CITED 

i  American  Public  Health  Association.    Laboratory  Section. 

1912.     Standard  methods  for  the  examination  of  water  and  sewage.    Ed.  2, 
144  pp.,  bibl.,  pp.  137-140. 
2  Ames,  J.  W.,  and  Schollenberger,  C.  J. 

1916.     Accumulation  of  salts  in  Ohio  soils.    Soil  Sci.,  vol.  1,  pp.  575-578. 
a  Bauer,  F.  C. 

1920.     The    effect   of   leaching   on    the    availability   of    rock   phosphate    to 
corn.     Soil  Sci.,  vol.  9,  pp.  235-247. 
<  Blair,  A.  W.,  and  Prince,  A.  L. 

1920.     The  lime  requirement  of  soils  according  to  the  Veitch  method,  com- 
pared with  the  hydrogen-ion  concentration  of  the  soil  extract.    Soil 
Sci.,  vol.  9,  pp.  253-259,  fig.. 2. 
s  Burd,  J.  S. 

1918.     Water  extractions  of  soils  as  criteria  of  their  crop-producing  power. 
Jour.  Agr.  Bes.,  vol.  12,  no.  6,  pp.  297-309. 
o  Christie,  A.  W.,  and  Martin,  J.  C. 

1918.     The  chemical  effects  of  CaO  and  CaC03  on  the  soil.     Part  II.  The 
effect   of   water-soluble   nutrients   in   soils.     Soil   Sci..   vol.   5,   pp. 
383-392. 
i  Coffee,  G.  N.,  and  Tuttle,  H.  F. 

1915.  Pot  tests  with  fertilizers  compared  with  field  trials.     Jour.  Am.  Soc. 

Agron.,  vol.  7,  pp.  129-139. 
s  Conner,  S.  D. 

1916.  Acid  soils  and  the  effect  of  acid  phosphate  and  other  fertilizers  upon 

them.    Jour.  Indus,  and  Eng.  Chem.,  vol.  8,  pp.  35-40. 
s  Conner,  S.  D. 

1917.  Excess  soluble  salts  in  humid  soils.     Jour.  Am.  Soc.  Agron.,  vol.  9, 

pp.  297-301. 
io  Davenport,  C  B. 

1904.     Statistical  methods.    John  Wiley  and  Sons,  New  York. 
11  Fraps,  G.  S. 

1915.     Effect   of   additions   on   availability   of   soil    phosphates.      Texas   Agr. 
Expt.  Sta.  Bull.  178,  15  pp. 
i2  Fred,  E.  B.,  and  Davenport,  A. 

1918.  Influence  of  reaction  on  nitrogen-assimilating  bacteria.     Jour.  Agr. 

Ees.,  vol.  14,  pp.  317-336,  fig.  1. 
i3  Greaves,  J.  E.,  and  Carter,  E.  G. 

1919.  The  action  of  some  common  soil  amendments.    Soil  Sci.,  vol.  7,  no.  2, 

pp.  121-160,  fig.  2. 
i*  Guthrie,  F.  B.,  and  Cohen,  B. 

1907.     Note  on  the  effect  of  lime  upon  the  availability  of  the  soil  constitu- 
ents.   Jour,  and  Proc.  Boy.  Soc.  N.  S.  W.,  vol.  41,  pp.  61-66. 
is  Hager,  G. 

1918.     The  injurious  actions  of  potassium  and  sodium  salts  on  the  structure 
of  soils  and  their  causes.     Jour.  Landw.,  vol.  66,  pp.  241-286. 


394  University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 

is  Hartwell,  B.  L.,  and  Kellogg,  J.  W. 

1905.  The  phosphoric  acid  removed  by  crops,  by  dilute  nitric  acid  and  by 

ammonium  hydroxide  from  a  limed  and  an  unlimed  soil.  18th  Ann. 
Ept.  R.  I.  Agr.  Expt.  Sta.,  pp.  253-255. 

i"  Hartwell,  B.  L.,  and  Pember,  F.  R. 

1918.  Aluminum  as  a  factor  influencing  the  effect  of  acid  soils  on  different 
crops.    Jour.  Am.  Soc.  Agron.,  vol.  10,  pp.  45-47. 

18  Habtwell,  B.  L.,  and  Pember,  F.  R. 

1918.  The  presence   of  aluminum   as   a   reason   for  the   difference   in   the 

effect  of  so-called  acid  soil  on  barley  and  rye.  Soil  Sci.,  vol.  6, 
pp.  259-277,  plate  1. 

is  Hibbard,  P.  L. 

1919.  The    alkalimetric    determination    of    small    amounts    of    magnesium. 

Jour.  Indus,  and  Eng.  Chem.,  vol.  11,  pp.  753-757. 

20  Hibbard,  P.  L. 

1919.  The  volumetric  determination  of  sulfates  by  oxidation  of  benzidine 

sulfate  with  KMn04.     Soil  Sci.,  vol.  8,  pp.  61-65. 

21  HOAGLAND,   D.  R. 

1918.  The  freezing  point  method  as  an  index  of  variations  in  the  soil 
solution  due  to  season  and  crop  growth.  Jour.  Agr.  Res.,  vol.  12, 
pp.  369-395,  fig.  9. 

22  HOROATH,  BELA  VON 

1916.  The  classification  of  soils  according  to  their  electric  conductivity. 
Intern.  Mitt.  Bodenk.,  vol  6,  p.  231.  Abstract  in  Chem.  Abs.,  vol. 
13,  p.  488. 

23  Jensen,  C.  A. 

1916.  Solubility  of  plant-food  elements  as  modified  by  fertilizers.  Jour. 
Am.  Chem.  Soc,  vol.  8,  no.  2,  pp.  100-105. 

24  Joffe,  J.  S. 

1920.  Hydrogen-ion  concentration  measurements  of  soils  in  connection  with 

their  "lime-requirements."     Soil  Sci.,  vol.  9,  pp.  261-266,  fig.  2. 
23  King,  F.  H. 

1906.  Investigations  in  soil  management,  being  three  of  six  papers  on  the 

influence  of  soil  management  upon  the  water-soluble  salts  in  soils 
and  the  yield  of  crops.  168  pp.,  21  figs.  Madison,  Wis.  (Pub.  by 
author. ) 

20  King,  F.  H. 

1904.  Investigations  in  soil  management.  U.  S.  D.  A.  Bur.  Soils,  Bull.  26, 
205  pp.,  9  figs.,  4  plates. 

27  Knight,  H.  G. 

1920.  Acidity  and  aeidimetry  of  soils.  III.  Comparison  of  methods  for 
determining  lime  requirements  of  soils  with  hydrogen  electrode. 
IV.  Proposed  method  for  determination  of  lime  requirement  of 
soils.     Jour.  Indus,  and  Eng.  Chem.,  vol.  12,  pp.  559-562. 

-8  Lipman,  C.  B. 

1918.  A  revolution  in  the  theories  and  methods  of  soil  chemistry.  Pro- 
ceedings of  Thirty-eighth  Annual  Meeting  of  Society  for  Promotion 
of  Agricultural  Science,  pp.  33—40. 


1922]  Burgess:  Studies  on  Marsh  Soil  Unproductive  for  Peas  395 

29  Lipman,  C.  B.,  and  Geeicke,  W.  F. 

1918.  Does  CaC03  or  CaSO,  treatment  affect  the  solubility  of  the  soil's 

constituents?      Univ.   Calif.   PubL   in   Agri.   Sei.,  vol.   3,   no.    10,   pp. 

271-282. 

30  Lyon,  T.  L. 

1911.     Some  experiments  to  estimate  errors  in  field  plot  tests.     Proc.  Am. 
Soc.  Agron.,  vol.  3,  pp.  89-114. 

si  MacIntire,  W.  H. 

1919.  The  liberation  of  native  soil  potassium  induced  by  different  calcic 

and  magnesic  materials,  as  measured  by  lysimeter  leachings.     Soil 
Sei.,  vol.  8,  pp.  337-394,  plate  1. 

32  McCool,  M.  M.,  and  Millar,  C.  E. 

1918.  Soluble  salt  content  of  soils  and  some  factors  affecting  it.     Mich. 

Agr.  Expt.  Sta.  Tech.  Bull.  43. 

33  McCool,  M.  M.,  and  Millar,  C.  E. 

1920.  The  effect  of  calcium  sulfate  on  the  solubility  of  soils.     Jour.  Agr. 

Eesearch,  vol.  19,  no.  2,  pp.  47-54. 

3*  Millar,  C.  E. 

1919.  The  comparative  rate  of  formation  of  soluble  material  in   cropped 

and  virgin  soils  as  measured  by  the  freezing  point  method.     Soil 
Sei.,  vol.  7,  pp.  253-257. 

35  MlYAKE,  K. 

1916.  The  toxic  action  of  soluble  aluminum  salts  upon  the  growth  of  the 

rice  plant.     Jour.  Biol.  Chem.,  vol.  25,  pp.  23-28. 

36  MlRASOL,  J.   J. 

1920.  Aluminum  as  a  factor  in  soil  acidity.    Soil  Sei.,  vol.  10,  pp.  153-217, 

plates  1-12. 

37  Morgan,  J.  O. 

1911.     The   effect  of   soil   moisture   and  temperature   on   the   availability   of 
plant  nutrients  in  the  soil.     Proe.  Am.  Soe.  Agron.,  vol.  3,  pp.  191- 
249.     (See  pp.  210-212.) 
ss  Morse,  F.  W. 

1918.  Effect   of  fertilizers  on  hydrogen-ion   concentration   in   soils.     Jour. 

Indus,  and  Eng.  Chem.,  vol.  10,  pp.  125-126. 
so  Ostwald  and  Luther 

1910.     Hand-  und  Hulfsbueh  zur  Ausfuhrung  Physiko-Cliemischer  Messungen 
(dritte  Aufiage).     See  pp.  461-477. 
40  Russell,  E.  J. 

1917.  Soil  conditions  and  plant  growth.    Ed.  3,  Longmans,  Green  and  Co., 

London  and  New  York. 
4i  Sharp,  L.  T. 

1916.     Fundamental    inter-relationships    between    soluble    salts   and   soil   col- 
loids.    Univ.  Calif.  Publ.  in  Agr.  Sei.,  vol.  1,  pp.  291-339,  3  figs. 

42  Sharp,  L.  T.,  and  Hoagland,  D.  R. 

1916.     Acidity  and  absorption  in  soils  as  measured  by  the  hydrogen  elec- 
trode.    Jour.  Agr.  Res.  vol.  7,  no.  3,  pp.  123-145,  1  fig. 

43  Spurway,  C.  H. 

1919.  The  effect  of  fertilizer  salts  treatments  on  the  composition  of  soil 

extracts.    Mich.  Agr.  Expt.  Sta.  Tech.  Bull.  45. 


:'>!»G  University  of  California  Publications  in  Agricultural  Sciences       [Vol.  4 

**  Stewart,  G.  R. 

1918.  Effect  of  season  and  crop  growth  in  modifying  the  soil  extract. 
Jour.  Agr.  Res.,  vol.  12,  no.  6,  pp.  311-368. 

«  Truog,  E.,  and  Sykora,  J. 

1917.  Soil  constituents  which  inhibit  the  action  of  plant  toxins.    Soil  Sci., 

vol.  3,  pp.  333-351,  plate  5.     Lit.  cit,  pp.  349-351. 

46  Watt,  R.  D. 

1909.  An    interesting    soil    problem.      Transvaal    Agr.    Jour.,    vol.    7,    pp. 

428-429. 

*i  Waynick,  D.  D. 

1918.  Variability  in  soils  and  its  significance  to  past  and  future  soil  investi- 

gations. I.  A  statistical  study  of  nitrification  in  soils.  Univ.  of 
Calif.  Publ.  in  Agr.  Sci.,  vol.  3,  no.  9,  pp.  243-270. 

48  Waynick,  D.  D.,  and  Sharp,  L.  T. 

1919.  Variability  in  soils  and  its  significance  to  past  and  future  soils  in- 

vestigations. II.  Variations  in  nitrogen  and  carbon  in  field  soils 
and  their  relation  to  the  accuracy  of  field  trials.  Univ.  of  Calif. 
Publ.  in  Agr.  Sci.,  vol.  4,  no.  5,  pp.  121-139. 

49  Wheeler,  H.  J.,  Brown,  B.  E.,  and  Hogenson,  J.  C. 

1903.  A  comparison  of  results  obtained  by  the  method  of  cultures  in  paraffined 
wire  pots  with  field  results  on  the  same  soil.  R.  I.  Agr.  Expt.  Sta., 
Bull.  109,  16  pp. 

so  Wood,  T.  B.,  and  Stratton,  F.  J.  M. 

1910.  The  interpretation  of  experimental  results.     Jour.  Agr.  Sci.    (Lon- 

don), vol.  3,  pp.  417-440,  figs.  10. 

si  Wood,  T.  B. 

1911.  The  interpretation  of  experimental  results.    Jour.  Bd.  Agr.  (London), 

vol.  18  (Supp.  no.  7),  pp.  15-37,  fig.  2. 


